In-plane switching mode active matrix type liquid crystal display device and method of fabricating the same

ABSTRACT

An in-plane switching mode active matrix type liquid crystal display device includes a first substrate, a second substrate located opposing the first substrate, and a liquid crystal layer sandwiched between the first and second substrates. The first substrate includes a thin film transistor, a pixel electrode each associated to a pixel to be driven, a common electrode to which a reference voltage is applied, data lines, a scanning line, and common electrode lines. Molecular axes of liquid crystal are rotated in a plane parallel with the first substrate by an electric field substantially parallel with a plane of the first substrate to thereby display certain images. The common electrode is composed of transparent material, and are formed on a layer located closer to the liquid crystal layer than the data lines. The common electrode entirely overlaps the data lines except an area where the data lines are located in the vicinity of the scanning line. The liquid crystal display device further includes a light-impermeable layer in an area where the common electrode entirely overlaps the data lines. The light-impermeable layer is comprised of a black matrix layer having a width smaller than a width of the common electrode.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a liquid crystal display device and amethod of fabricating the same, and more particularly to an in-planeswitching mode active matrix type liquid crystal display device and amethod of fabricating the same.

[0003] 2. Description of the Related Art

[0004] A liquid crystal display device may be grouped into two types inone of which molecular axes of aligned liquid crystal molecules arerotated in a plane perpendicular to a substrate to display a certainimage, and in the other of which molecular axes of aligned liquidcrystal molecules are rotated in a plane parallel with a substrate todisplay a certain image.

[0005] A typical one in the former type is a twisted nematic (TN) modeliquid crystal display device, and the latter type is called an in-planeswitching (IPS) mode liquid crystal display device.

[0006] Since a viewer looks only at a direction in which minor axes ofliquid crystal molecules extend, even if he/she moves his/her eye point,in an IPS mode liquid crystal display device, how liquid crystalmolecules stand is not dependent on a viewing angle, and accordingly, anIPS liquid crystal display device can present a wider viewing angle to aviewer than a TN mode liquid crystal display device.

[0007] Hence, an IPS mode liquid crystal display device has been morepopular these days than a TN mode liquid crystal display device.

[0008] For instance, Japanese Unexamined Patent Publication No.07-036058 has suggested an example of an IPS mode liquid crystal displaydevice. Attempts have been made to present a higher aperture ratio in anIPS mode liquid crystal display device, for instance, in JapaneseUnexamined Patent Publications Nos. 11-119237, 10-186407, 9-236820, and6-202127.

[0009] The IPS mode liquid crystal display device suggested in JapaneseUnexamined Patent Publication No. 11-119237 is characterized in thatboth a drive electrode (which corresponds to the pixel electrode in thepresent invention) and an opposing electrode (which corresponds to thecommon electrode in the present invention) are formed in a layer whichis different from a layer in which a signal line is formed, and islocated closer to a liquid crystal layer. This structure ensures thatthe opposing electrode is less influenced by an electric field generateddue to a voltage difference between the signal line and the opposingelectrode formed at an end of an opening and adjacent to the signalline, and hence, it would be possible to locate the opposing electrodecloser to the signal line. As a result, it would be possible to increasean area of the opening.

[0010] Japanese Unexamined Patent Publication No. 11-119237 furthersuggests that the drive electrode and the opposing electrode arecomposed of transparent material such as ITO. However, it is notdisclosed that the opposing electrode overlaps the signal line.

[0011] Japanese Unexamined Patent Publication No. 11-119237 furthersuggests an IPS mode liquid crystal display device in which both thedrive electrode and the opposing electrode are formed in a layer locatedabove a layer in which the signal line is formed, and the opposingelectrode overlaps the signal line. This structure ensures that thedrive and opposing electrodes are less influenced by an electric fieldleaking out of the signal line, and that a light is not leaked out of aslit formed between the signal line and the opposing electrode.

[0012] However, there is no suggestion that the drive and opposingelectrodes are formed as transparent electrodes, because the opposingelectrode is formed to overlap the signal line for the purpose ofinterrupting a light leaking out of the slit.

[0013] In the IPS mode liquid crystal display device disclosed inJapanese Unexamined Patent Publication No. 10-186407, an electricallyinsulating layer is formed between a common electrode layer of which acommon electrode is formed and a data line layer of which a data line isformed, and the common electrode layer is located closer to a liquidcrystal layer than the data line layer. The common electrode overlaps aparticular area of the data line in a particular area. The commonelectrode entirely overlaps the data line, preventing leakage of anelectric field, and the common electrode partially overlaps the dataline, ensuring reduction in a parasitic capacity formed between the dataline and the common electrode.

[0014] However, Japanese Unexamined Patent Publication No. 10-186407does not disclose and suggest a common electrode composed of transparentmaterial.

[0015] In the IPS mode liquid crystal display device disclosed inJapanese Unexamined Patent Publication No. 9-236820, each of opposingelectrodes is comprised of thin strip-shaped electrodes parallel withsource bus lines (which correspond to the data lines in the presentinvention) through which a pixel signal is transmitted to a pixelelectrode. The opposing electrodes and the source bus lines are stackedone on another with transparent insulating layers being sandwichedtherebetween. The opposing electrodes and the source bus lines arelocated at the same position with respect to a direction in which alight passes through the liquid crystal display device.

[0016] Japanese Unexamined Patent Publication No. 9-236820 describesthat it would be possible to increase an aperture ratio of pixels, ifthe opposing and pixel electrode were composed of transparent material.However, the Publication further describes that since transparentmaterial has a high resistance, a voltage difference would be generated,disturbing driving the electrodes to display images, and that atransparent electrode is quite expensive.

[0017] An IPS mode liquid crystal display device disclosed in JapaneseUnexamined Patent Publication No. 6-202127 is designed to have a drivercomprised of an active device and is characterized in that a signal linethrough which an image signal is transmitted to the active device iscovered in an area facing a liquid crystal layer with an electricalconductor with an electrical insulator being sandwiched therebetween.

[0018] However, the Publication never discloses and suggests that asignal line is shielded with a transparent electrode.

[0019] An IPS mode liquid crystal display device disclosed in JapaneseUnexamined Patent Publication No. 10-307295 is characterized by aplurality of sub-areas for compensating for colored images. As anexample, the Publication suggests a method of preventing images frombeing colored, including the step of generating electric fields havingdifferent directions in first and second sub-areas, to thereby rotateliquid crystal molecules in different directions in the first and secondsub-areas, ensuring that optical characteristics of the first and secondsub-areas are compensated for to each other when a viewer obliquelyviews the liquid crystal display device.

[0020] The IPS mode liquid crystal display devices disclosed in theabove-mentioned Publications have an object of increasing an apertureratio, and enhancing a brightness of displayed images.

[0021] Since there is generated a voltage difference between a data lineand an opposing electrode or a common electrode, an electric field isgenerated due to the voltage difference. If the electric field reachessuch a region that a display region located between a pixel electrodeand a common electrode is influenced by the electric field, alignment inliquid crystal molecules is disturbed. For instance, when a white windowis to be displayed on a screen under black background, there would becaused a problem called vertical cross-talk by which pixels which shoulddisplay black, associated with a data line driving pixels displayingwhite, display gray.

[0022] In order to avoid the vertical cross-talk problem, it would benecessary to terminate the electric field with the common electrodehaving a width extending outwardly at opposite edges of the data linefor shielding an electric filed associated with the data line, or tocover the data line with an electrode to which a voltage exerting noinfluence on images is applied, such as the common electrode.

[0023] In order to increase an aperture ratio, it would be preferable tocover the data line with the common electrode, as mentioned in thelatter.

[0024] However, the conventional liquid crystal display devicessuggested in the above-mentioned Publications are accompanied withproblems of incomplete shield and reduction in an efficiency with whicha light is used which reduction is caused by a common electrode composedof light-impermeable material.

[0025] The conventional liquid crystal display devices suggested in theabove-mentioned Publications have an object of enhancing an apertureratio, however, there is a need of further enhancement of an apertureratio.

SUMMARY OF THE INVENTION

[0026] In view of the above-mentioned problems in the conventionalliquid crystal display devices, it is an object of the present inventionto provide an in-plane switching (IPS) mode liquid crystal displaydevice which is capable of solving the vertical cross-talk problem andincreasing an aperture ratio.

[0027] Specifically in comparison with the above-mentioned conventionalliquid crystal display devices, the first object of the presentinvention is to provide an IPS mode liquid crystal display device whichis capable of preventing occurrence of vertical cross-talk withoutreduction in an aperture ratio.

[0028] In order to accomplish the above-mentioned first object, a dataline is designed to be overlapped by a transparent common electrode forshielding an electric filed leaking out of the data line in the IPS modeliquid crystal display device in accordance with the present invention.However, this structure is accompanied with a problem that since atransparent material has a high resistance, there would be generated avoltage difference which would prevent electrodes from being properlydriven for displaying images, as pointed out in the above-mentionedJapanese Unexamined Patent Publication No. 9-236820. Accordingly, thesecond object of the present invention to provide an IPS mode liquidcrystal display device in which a common electrode comprised of atransparent electrode overlaps a data line, and the common electrodecould have a reduced resistance.

[0029] In order to accomplish the second object, a transparent electrodeoverlapping a data line is electrically connected to a common electrodeline through a contact hole in each of pixels.

[0030] Even if the above-mentioned objects were accomplished, theproblem of reduction in an aperture ratio remains unsolved. Accordingly,the third object of the present invention is to provide an IPS modeliquid crystal display device which is capable of narrowing alight-impermeable film such as a black matrix film which was used in aconventional IPS mode liquid crystal display device to prevent verticalcross-talk, which is generated due to a leaked electric field, fromappearing in a displayed image.

[0031] In order to accomplish the above-mentioned third object, a blackmatrix layer facing data lines is designed to have a width smaller thana width of a common electrode overlapping the data lines, and alight-impermeable film is designed not to be formed between the commonelectrode overlapping the data line and the pixel electrode locatedadjacent to the common electrode, when viewed as a plan view, in the IPSmode liquid crystal display device in accordance with the presentinvention.

[0032] As the above-mentioned Japanese Unexamined Patent Publication No.9-236820 has pointed out, there is a problem that a transparentelectrode is expensive. Accordingly, the fourth object of the presentinvention is to provide an IPS mode liquid crystal display device inwhich a transparent electrode can be fabricated at low cost.

[0033] In order to accomplish the fourth object, the transparentelectrode is composed of ITO, and the transparent electrode isfabricated without an increase in the number of fabrication steps byfabricating the ITO transparent electrode concurrently with a terminalcomposed of ITO.

[0034] As pointed out in the above-mentioned Japanese Unexamined PatentPublication No. 10-186407, the problem that a parasitic capacity isincreased between a data line and a common electrode, if the commonelectrode entirely overlaps the data line, remains unsolved.Accordingly, the fifth object of the present invention is to provide anIPS mode liquid crystal display device in which a data line is almostentirely overlapped by a common electrode without an increase in aparasitic capacity between a data line and a common electrode.

[0035] In order to accomplish the fifth object, a common electrodecomposed of ITO is formed in a layer closer to a liquid crystal layerthan a data line with an interlayer insulating layer being sandwichedtherebetween, and the interlayer insulating layer is composed of organicmaterial having a low dielectric constant.

[0036] Though the above-mentioned Publications do not point out, if acommon electrode shielding a data line is designed to be composed of anordinary metal other than ITO, reliability of a resultant liquid crystaldisplay device is reduced in comparison with a liquid crystal displaydevice having a common electrode composed of ITO. Accordingly, the sixthobject of the present invention is to provide an IPS mode liquid crystaldisplay device in which a data line is shielded with a more reliabletransparent material.

[0037] In one aspect of the present invention, there is provided anin-plane switching mode active matrix type liquid crystal display deviceincluding (a) a first substrate, (b) a second substrate located opposingthe first substrate, and (c) a liquid crystal layer sandwiched betweenthe first and second substrates, wherein the first substrate includes(a1) a thin film transistor having a gate electrode, a drain electrodeand a source electrode, (a2) a pixel electrode each associated to apixel to be driven, (a3) a common electrode to which a reference voltageis applied, (a4) data lines, (a5) a scanning line, and (a6) commonelectrode lines, the gate electrode is electrically connected to thescanning line, the drain electrode is electrically connected to the datalines, the source electrode is electrically connected to the pixelelectrode, and the common electrode is electrically connected to thecommon electrode lines, molecular axes of liquid crystal in the liquidcrystal layer are rotated in a plane parallel with the first substrateby an electric field substantially parallel with a plane of the firstsubstrate and to be applied between the pixel electrode and the commonelectrode, to thereby display certain images, the common electrode iscomposed of transparent material, and are formed on a layer locatedcloser to the liquid crystal layer than the data lines, the commonelectrode entirely overlaps the data lines with an insulating layerbeing sandwiched therebetween except an area where the data lines arelocated in the vicinity of the scanning line, the in-plane switchingmode active matrix type liquid crystal display device further includes alight-impermeable layer in an area where the common electrode entirelyoverlaps the data lines, the light-impermeable layer is formed on thesecond substrate or on the first substrate such that thelight-impermeable layer and the liquid crystal layer are located at thesame side with respect to the data lines and that the light-impermeablelayer faces the data lines, the light-impermeable layer is comprised ofa black matrix layer or multi-layered color layers, the black matrixlayer or the multi-layered color layers has a width smaller than a widthof the common electrode overlapping the data lines.

[0038] The above-mentioned in-plane switching mode active matrix typeliquid crystal display device accomplishes the above-mentioned first tothird objects. Specifically, the in-plane switching mode active matrixtype liquid crystal display device which (a) prevents verticalcross-talk without reduction in an aperture ratio, in which (b) the dataline is overlapped by the transparent electrode electrically connectedto the common electrode, and the common electrode could have a reducedresistance, and which (c) is capable of narrowing a light-impermeablefilm such as a black matrix film which was used in a conventional IPSmode liquid crystal display device to prevent vertical cross-talk, whichis generated due to a leaked electric field, from appearing in adisplayed image.

[0039] Hereinbelow is explained the reason why the above-mentionedin-plane switching mode active matrix type liquid crystal display devicecan accomplish the first and third objects.

[0040]FIG. 1 is a partial cross-sectional view of the above-mentionedconventional liquid crystal display device 10A. FIG. 1 illustrates onlyparts necessary for explanation for the purpose of simplifyingexplanation.

[0041] The liquid crystal display device 10A is comprised of an activedevice substrate 11A, an opposing substrate 12A, and a liquid crystallayer 13A sandwiched between the active device substrate 11A and theopposing substrate 12A.

[0042] The opposing substrate 12A is comprised of a black matrix layer17A acting as a light-impermeable film for interrupting unnecessarylights, a color layer 18A partially covering the black matrix layer 17Atherewith, an over-coating layer 19A formed covering the black matrixlayer 17A and the color layer 18A therewith, and an alignment film 20Aformed entirely over the over-coating layer 19A.

[0043] The active device substrate 11A is comprised of a commonelectrode 26A formed on a glass substrate (not illustrated), aninterlayer insulating film 25A formed on the glass substrate, coveringthe common electrode 26A therewith, a data line 24A formed on theinterlayer insulating film 25A, a pixel electrode 27A formed on theinterlayer insulating film 25A, a passivation film 37A formed on theinterlayer insulating film 25A, covering the data line 24A and the pixelelectrode 27A therewith, and an alignment film 31A formed on thepassivation film 37A.

[0044] In the liquid crystal display device 10A illustrated in FIG. 1,it was necessary for the common electrode 26A formed adjacent to thedata line 24A to have a sufficiently wide width in order to absorbtherein an electric field leaking out of the data line 24A. Since thecommon electrode 26A is composed of opaque material of which a gate lineis composed, it is not avoidable that an area defining an opening OPextends inwardly from a right edge of the common electrode 26A.

[0045] In addition, it was also necessary for the black matrix layer 17Ato have a width greater than and entirely covering a width of the dataline 24A in order to interrupt a light S leading out of a gap betweenthe data line 24A and the common electrode 26A.

[0046] For instance, the black matrix layer 17A in the liquid crystaldisplay device 10A was designed to extend beyond a gap between the dataline 24A and the common electrode 26A by 8 μm or greater, takingmisregistration between the active device substrate 11A and the opposingsubstrate 12A acting as a color filter into consideration.

[0047] As explained so far it was quite difficult in the conventionalliquid crystal display device 10A to increase an aperture ratio, becausethe liquid crystal display device 10A could merely have a limited areaas an opening OP, and it was necessary for the black matrix layer 17A toextend beyond the above-mentioned gap.

[0048]FIG. 2 is a partial cross-sectional view of a liquid crystaldisplay device 10 in accordance with the present invention. Similarly toFIG. 1, FIG. 2 illustrates only parts necessary for explanation for thepurpose of simplifying explanation.

[0049] The liquid crystal display device 10 is comprised of an activedevice substrate 11, an opposing substrate 12, and a liquid crystallayer 13 sandwiched between the active device substrate 11 and theopposing substrate 12.

[0050] The opposing substrate 12 is comprised of a black matrix layer17, a color layer 18 partially covering the black matrix layer 17therewith, an over-coating layer 19 formed covering the black matrixlayer 17 and the color layer 18 therewith, and an alignment film 20formed entirely over the over-coating layer 19.

[0051] The active device substrate 11 is comprised of a first interlayerinsulating film 23, a data line 24 formed on the first interlayerinsulating film 23, a second interlayer insulating film 25 formed on thefirst interlayer insulating film 23, covering the data line 24therewith, a common electrode 26 formed on the second interlayerinsulating film 25, a pixel electrode 27 formed on the second interlayerinsulating film 25, and an alignment film 31 formed on the secondinterlayer insulating film 25, covering the common electrode 26 and thepixel electrode 27 therewith.

[0052] The common electrode 26 is designed to entirely overlap the dataline 24, and the black matrix layer 17 is designed to have a widthsmaller than a width of the common electrode 26. Both of the commonelectrode 26 and the pixel electrode 27 are composed of indium-tin-oxide(ITO) as one of transparent materials.

[0053] In accordance with the liquid crystal display device 10, anelectric field leaking out of the data line 24 is completely shielded bythe common electrode 26 located above the data line 24. Hence, asillustrated in FIG. 2, it is possible to have an area defining anopening OP which extends inwardly from a right edge of the commonelectrode 26, which opening OP is wider than the opening OP obtained inthe conventional liquid crystal display device 10A illustrated in FIG.1.

[0054] That is, the liquid crystal display device 10 in accordance withthe present invention can present a greater aperture ratio than that ofthe conventional liquid crystal display device 10A.

[0055] In addition, light leakage can be sufficiently prevented, only ifa light leaking out of a pixel located adjacent to the black matrixlayer 17 is prevented from leaking out, in the liquid crystal displaydevice 10 in accordance with the present invention. Accordingly, it isno longer necessary for the black matrix layer 17 to have a widthgreater than a width of the data line 24, even if misregistrationbetween the active device substrate 11 and the opposing substrate 12 istaken into consideration.

[0056] For instance, if the black matrix layer 17 had a width of 6 μm orgreater as long as the data line 24 overlaps the black matrix layer 17,it would be possible for the black matrix layer 17 to sufficientlyinterrupt lights.

[0057]FIG. 3 is a graph showing the results of simulating how anelectric field leaking out of the data line 24 is shielded in the liquidcrystal display device wherein the common electrode 26 entirely overlapsthe data line 24.

[0058] In the simulation, a profile of potential and a rate at which alight passes through the liquid crystal display device in a unit cellare calculated on the assumption that pixels are all black, a voltage of0V is applied to both the pixel electrode 27 and the common electrode26, and a voltage of 5V is applied to the drain.

[0059] As shown in FIG. 3, a rate Z at which a light passe through theliquid crystal display device is kept zero (0). This means that anelectric field leaking out of the data line 24 is completely shielded bythe common electrode 26.

[0060] The black matrix layer 17 may be replaced with alight-impermeable layer having multi-layered color layers, in whichcase, it is no longer necessary to form the black matrix layer 17, andhence, it would be possible to increase a fabrication efficiency of theliquid crystal display device.

[0061] It is preferable that the common electrode is electricallyconnected to the common electrode lines through a contact hole in eachof pixels.

[0062] It would be possible to reduce a resistance of the commonelectrode by electrically connecting the common electrode to the commonelectrode lines through a contact hole in each of pixels. As a result,it would be possible to solve the problem that transparent material hasa high resistance.

[0063] It is preferable that one of the first and second substrates iscomprised further of a color layer formed in a line.

[0064] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes a reverse-rotationpreventing structure in a sub pixel area in which all liquid crystalmolecules are rotated in the same direction, for preventing liquidcrystal molecules from rotating in a direction opposite to the samedirection, the reverse-rotation preventing structure including anauxiliary electrode to which a voltage equal to a voltage of at leastone of the pixel electrode and the common electrode is applied such thatan initial alignment orientation of liquid crystal molecules overlaps adirection of an electric field generated in the sub pixel area in allsub-areas in the sub pixel areas, if the initial alignment orientationrotates by an acute angle.

[0065] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film formed below the common electrode overlapping the datalines. The interlayer insulating film is comprised of an upper layer anda lower layered, and the upper layer is formed only below a portion ofthe common electrode which portion overlaps the data lines.

[0066] By including such an interlayer insulating film, it is no longernecessary to form an interlayer insulating film having a too much areabetween a common electrode and a data line, and it would be possible toalmost entirely overlap the data line with the common electrode withoutan increase in a parasitic capacity to be formed between the commonelectrode and the data line.

[0067] It is preferable that the common electrode is wider than the datalines at opposite ends in a width-wise direction thereof by 1.5 μm orgreater.

[0068] By designing the common electrode to be wider than the data linesat opposite ends in a width-wise direction thereof by 1.5 μm or greater,it would be possible to make an allowable maximum light passing at aside of the data line, equal to or smaller than {fraction (1/100)} of alight passing through a pixel when white is displayed on the pixel.

[0069] It is preferable the black matrix layer has a width smaller thana width of the data lines, and overlaps the data lines in its entirelength.

[0070] As illustrated in FIG. 2, if the black matrix layer 17 has awidth smaller than a width of the data line 24, it would be possible tomake use of all light passing through extensions of the transparentcommon electrode 26 overlapping the data line 24, ensuring enhancementin a ratio at which a light passes through a panel.

[0071] It is preferable that the black matrix layer is formed on thesecond substrate, and the black matrix layer facing the data lines has awidth equal to or greater than 6 μm.

[0072] If the black matrix layer had a width smaller than 6 μm, muchlight reflects at the data line 24, resulting in that a screen of thein-plane switching mode active matrix type liquid crystal display deviceis hard to be seen under bright circumstance.

[0073] It is preferable that the black matrix layer overlaps thescanning line and a region therearound, and an area sandwiched betweenthe scanning line and the pixel electrode and a region therearound.

[0074] This ensures that the scanning line, the region and the area canbe shielded from light by the black matrix layer.

[0075] It is preferable that the pixel electrode is composed oftransparent material.

[0076] The pixel electrode composed of transparent material wouldfurther enhance an aperture ratio.

[0077] It is preferable that the common electrode and the pixelelectrode are formed in a common layer.

[0078] Thus, it would be possible to form the common and pixelelectrodes in a single step, ensuring enhancement of a fabricationyield, or the in-plane switching mode active matrix type liquid crystaldisplay device in accordance with the present invention can befabricated without an increase in the number of fabrication steps.

[0079] The in-plane switching mode active matrix type liquid crystaldisplay device may further include an interlayer insulating layer formedin a layer located immediately below the common electrode, and a pixelauxiliary electrode comprised of a single or a plurality of layer(s)formed below the interlayer insulating layer, wherein the pixelauxiliary electrode is preferably electrically connected to the sourceelectrode, and kept at a voltage equal to a voltage of the pixelelectrode. The pixel auxiliary electrode is preferably composed ofopaque metal.

[0080] Though the pixel auxiliary electrode composed of opaque metalslightly reduces transmissivity, it would be possible to form storagecapacities above and below a pixel by electrically connecting the pixelelectrode to one another through the pixel auxiliary electrode, ensuringhigher storage capacitance and higher quality in displaying images.

[0081] It is preferable that the pixel auxiliary electrode is at leastpartially formed below the pixel electrode formed in a layer in whichthe common electrode is formed, and having a plurality of comb-teeth.

[0082] Since an electric field is vertically applied to liquid crystalimmediately above the transparent pixel electrode, the liquid crystalvertically stands with the result of reduction in light transmissivityin comparison with light transmissivity obtained in an area betweencomb-teeth electrodes. Accordingly, it would be possible to electricallyconnect the pixel auxiliary electrodes located at opposite sides of apixel, to each other without much reduction in an efficiency at which alight is used, by locating the pixel auxiliary electrode composed ofopaque material, just below the pixel electrode having a slightlysmaller transmissivity than that of the pixel auxiliary electrode.

[0083] It is also preferable that the in-plane switching mode activematrix type liquid crystal display device further includes an interlayerinsulating layer formed in a layer located immediately below the commonelectrode, and a common auxiliary electrode comprised of a single or aplurality of layer(s) formed below the interlayer insulating layer,wherein the common auxiliary electrode is electrically connected to thecommon electrode lines, and kept at a voltage equal to a voltage of thecommon electrode, and the common auxiliary electrode is composed ofopaque metal.

[0084] It would be possible to form storage capacitors both above andbelow a pixel by electrically connecting the common electrode to eachother, similarly to the common auxiliary electrodes, ensuring higherstorage capacitance and higher quality in displaying images.

[0085] It is preferable that the pixel auxiliary electrode is formedbelow the common electrode having a plurality of comb-teeth.

[0086] It would be possible to electrically connect the common auxiliaryelectrodes located at opposite sides of a pixel, to each other withoutmuch reduction in an efficiency at which a light is used, by locatingthe common auxiliary electrode composed of opaque material, just belowthe pixel electrode having a slightly smaller transmissivity than thatof the common auxiliary electrode. However, if the pixel auxiliaryelectrode were arranged below the common electrode, an electric fieldwould be generated between the common electrode and the pixel auxiliaryelectrode, resulting in that a desired horizontal electric field cannotbe applied to liquid crystal. Accordingly, it is preferable that thepixel auxiliary electrode is arranged just below the pixel electrode,and the common auxiliary electrode is arranged just below the commonelectrode.

[0087] It is preferable that a scanning line terminal, a data lineterminal and a common electrode line terminal are covered with orcomposed of a material of which the common electrode comprised oftransparent electrodes are composed.

[0088] This ensures it possible to form the common electrodeconcurrently with terminals of the liquid crystal display device,avoiding an increase in the fabrication steps necessary for forming thecommon electrode.

[0089] The in-plane switching mode active matrix type liquid crystaldisplay device may preferably further includes a reverse-rotationpreventing structure in a sub pixel area in which all liquid crystalmolecules are rotated in the same direction, for preventing liquidcrystal molecules from rotating in a direction opposite to the samedirection, wherein at least a part of edges of the pixel auxiliaryelectrodes and the common electrode lines is formed oblique such that aninitial alignment orientation of liquid crystal molecules overlaps adirection of an electric field generated in the sub pixel area in allsub-areas in the sub pixel areas, if the initial alignment orientationrotates by an acute angle.

[0090] By preventing molecular axes of liquid crystal molecules fromrotating in a reverse direction, it would be possible for the liquidcrystal display device to have improved display quality and reliability.

[0091] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes a passivation filmcovering the common electrode therewith.

[0092] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes a passivation filmcovering the pixel electrode therewith.

[0093] The passivation film covering the pixel or common electrodetherewith would relax an intensive electric field generated at edges ofthe pixel or common electrode, ensuring prevention of defects in bothalignment of liquid crystal molecules and displaying images.

[0094] It is preferable that the first substrate is formed with one of afirst contact hole electrically connecting the pixel electrode to thesource electrode, and a second contact hole electrically connecting thecommon electrode to the common electrode lines, the first and secondcontact holes being square or rectangular in shape, and having a sidehaving a length equal to or greater than 6 μm.

[0095] The first and second contact holes having a side having a lengthequal to or greater than 6 μm would ensure appropriate electricalcontact.

[0096] It is preferable that the first substrate is formed with one of afirst contact hole electrically connecting the pixel electrode to thesource electrode, and a second contact hole electrically connecting thecommon electrode to the common electrode lines, the first and secondcontact holes being covered at inner surfaces thereof with a metal film.

[0097] By covering the first and second contact holes at its innersurfaces with a metal film, it would be possible to reduce a resistancebetween the common electrode and the common electrode line both composedof a transparent metal, and enhance uniformity in displaying images.

[0098] For instance, the pixel electrode may be formed of a second metallayer of which the data lines are formed.

[0099] Since the pixel and common electrodes are comprised of differentlayers from each other, the pixel and common electrodes are no longershort-circuited with each other, ensuring enhancement in a fabricationyield.

[0100] It is preferable that the pixel electrode is formed of a secondmetal layer of which the drain electrode is formed, in an area in whichan image is displayed, and a portion of the common electrode other thana portion composed of transparent metal and overlapping the data linesis formed of a first metal layer of which the gate electrode is formed.

[0101] Since the pixel and common electrodes are comprised of differentlayers from each other, the pixel and common electrodes are no longershort-circuited with each other, ensuring enhancement in a fabricationyield. In addition, since the floating electrode comprised of the firstlayer is comprised of a layer of which the common electrode is alsocomprised, the floating electrode becomes a fixed electrode byelectrically connecting to the common electrode, ensuring enhancement indisplay quality.

[0102] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film sandwiched between the data lines and the commonelectrode overlapping the data lines and composed of transparent metal,the interlayer insulating film being formed only below the commonelectrode.

[0103] This ensures that it is no longer necessary to form an interlayerinsulating film between the common electrode and the data line in anarea which is large more than necessary, and hence, the data line can bealmost entirely covered with the common electrode without an increase ina parasitic capacity between the common electrode and the data line.

[0104] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film sandwiched between the data lines and the commonelectrode overlapping the data lines and composed of transparent metal,the interlayer insulating film being comprised of an inorganic film.

[0105] By composing the interlayer insulating film of an inorganicmaterial, the interlayer insulating film could have enhancedtransparency. In addition, it would be possible to enhance reliabilityof the thin film transistor.

[0106] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film sandwiched between the data lines and the commonelectrode overlapping the data lines and composed of transparent metal,the interlayer insulating film being comprised of an organic film.

[0107] Since an organic film has a smaller dielectric constant than thatof an inorganic film, the interlayer insulating film composed of organicmaterial would have a smaller dielectric constant than that of aninterlayer insulating film composed of inorganic material. In addition,a process of composing an interlay insulating film of an organicmaterial is simpler than a process of composing the same of an inorganicmaterial.

[0108] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film sandwiched between the data lines and the commonelectrode overlapping the data lines and composed of transparent metal,the interlayer insulating film being comprised of a first film comprisedof an inorganic film and a second film comprised of an organic film andcovering the first film therewith.

[0109] In comparison with an interlayer insulating film comprised onlyof an inorganic film, an interlayer insulating film having such amulti-layered structure could have a smaller dielectric constant. Inaddition, by designing the first film comprised of an inorganic film tomake contact with a semiconductor layer in the thin film transistor, andfurther by forming the second film on the first film, it would bepossible to form a stable interface between the first and second films,ensuring enhancement in reliability of the thin film transistor.

[0110] For instance, the inorganic film may be selected from a siliconnitride film, an inorganic polysilazane film, a silicon oxide film, or amulti-layered structure including two or more of them.

[0111] These inorganic films provide enhanced reliability to the thinfilm transistor.

[0112] For instance, the organic film may be selected from aphotosensitive acrylic resin film, a photosensitive polyimide film, abenzocyclobutene (BCB) film, an organic polysilazane film, or a siloxanefilm.

[0113] These organic films can be readily formed.

[0114] For instance, the first film may be comprised of a siliconnitride film and the second film may be comprised of a photosensitiveacrylic resin film or a photosensitive polyimide resin film.

[0115] The multi-layered structure including the above-mentioned firstand second films would reduce a dielectric constant of the interlayerinsulating film, and ensure enhancement in reliability of the thin filmtransistor.

[0116] It is preferable that the common electrode composed oftransparent metal and overlapping the data lines further overlaps anarea between the scanning line and the common electrode lines.

[0117] The common electrode having such a structure can shield anelectric field leaking out of the scanning line, and hence, it would bepossible to increase the display area controllable by an electric fieldto be generated between the pixel electrode and the common electrode,ensuring enhancement in an aperture ratio.

[0118] It is preferable that the common electrode composed oftransparent metal and overlapping the data lines further overlaps achannel region of the thin film transistor.

[0119] The common electrode having such a structure can prevent anelectric field from intruding to the thin film transistor from outsidethereof, ensuring enhancement in stability in the thin film transistorcharacteristic and reliability in displaying images.

[0120] It is preferable that a storage capacity is formed between thecommon electrode lines comprised of a first metal layer of which thegate electrode is formed, and a pixel auxiliary electrode comprised of asecond metal layer of which the drain electrode is formed.

[0121] By forming the common electrode lines comprised of a first metallayer and the pixel auxiliary electrode comprised of a second metallayer, it would be possible to form a storage capacity above and below apixel, ensuring an increase in a storage capacitance, which furtherensures that images can be stably displayed.

[0122] It is preferable that the common electrode lines are formed onopposite sides or on either side of the scanning line along the scanningline in a plan view of each of pixels.

[0123] By forming the common electrode lines in the above-mentionedmanner, a transparent area would be increased by an area occupied by thecommon electrode, because the common electrode is composed oftransparent material. This ensures enhancement in an aperture ration inthe in-plane switching mode active matrix type liquid crystal displaydevice. The common electrode lines formed on opposite sides of thescanning line could provide a greater storage capacitor than that of thecommon electrode lines formed on either side of the scanning line,ensuring that images can be displayed with enhanced stability.

[0124] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device may further include alight-impermeable layer electrically connected to the common electrodeand formed below the data lines in an area where the data lines are notoverlapped by both the black matrix layer and the multi-layered colorlayers, and the common electrode do not overlap the data lines.

[0125] The light-impermeable layer prevents light leakage, and hence,prevents disturbance in displaying images.

[0126] It is preferable that the gate electrode is comprised of a firstmetal layer and the drain electrode is comprised of a second metallayer, the first and second metal layers being comprised of one of achromium layer, an aluminum layer, a titanium layer, a molybdenum layer,a tungsten layer, and a multi-layered film including one or more ofthese layers.

[0127] These metal films ensure reduction in a resistance, andenhancement in reliability.

[0128] It is preferable that the pixel electrode and the sourceelectrode or the pixel auxiliary electrode formed of a second metallayer are electrically connected to each other through a first contacthole in each of pixels at one of upper and are lower sides when viewedfrom above, and the common electrode and the common electrode linesformed of a first metal layer are electrically connected to each otherthrough a second contact hole in each of pixels at the other of upperand lower sides when viewed from above.

[0129] By electrically connecting the common electrode to the commonelectrode line through a contact hole in each of pixels, as mentionedabove, it would be possible to reduce a resistance of the commonelectrode.

[0130] It is preferable that the transparent electrode is composed ofIndium-Tin-Oxide (ITO).

[0131] Indium-Tin-Oxide (ITO) is quite stable to electrochemicalreaction. Hence, the common and pixel electrodes both composed of ITOmay be designed to make direct contact with an alignment film, ensuringreliability of the in-plane switching mode active matrix type liquidcrystal display device in comparison with a liquid crystal displaydevice including common and pixel electrodes composed of any metal otherthan ITO.

[0132] It is preferable that a storage capacity is formed between thecommon electrode lines comprised of a first metal layer of which thegate electrode is formed, and a pixel auxiliary electrode comprised of asecond metal layer of which the drain electrode is formed.

[0133] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film formed between the data lines and the common electrode,the interlayer insulating film being comprised of a first film comprisedof an inorganic film, and a second film covering the first filmtherewith and comprised of an organic film, the first film having athickness equal to or greater than 0.25 μm.

[0134] Even if a pin-hole is generated in the second film between thedata lines and the common electrode overlapping the data lines, sincethe first film comprised of an inorganic film and having a thicknessequal to or greater than 0.25 μm have a sufficient high breakdownvoltage, it would be possible to prevent the data lines and the commonelectrode from short-circuiting to each other due to a dielectricbreakdown of an interlayer insulating film formed therebetween, while apanel is being fabricated or images are being displayed. This ensuresprevention of defects in the data lines.

[0135] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes a color layer formedon the first substrate.

[0136] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes a black matrix layerformed on the first substrate.

[0137] By designing the first substrate to have the black matrix layerand/or the color layer, they can be designed to overlap the data lineswith an increased accuracy, and accordingly, it would be possible forthe black matrix layer and the color layer to have a smaller width,ensuring an increase in an aperture ratio.

[0138] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film formed between the data lines and the common electrode,the interlayer insulating film including at least an organic film, theblack matrix or color layer being covered with the organic film.

[0139] The organic film of which the interlayer insulating film iscomposed prevents impurities contained in the color layer and/or theblack matrix layer from dissolving into the liquid crystal layer. Thisensures enhancement in reliability of the liquid crystal display device.

[0140] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film formed between the data lines and the common electrode,the interlayer insulating film being comprised of a first film comprisedof an inorganic film, and a second film covering the first filmtherewith and comprised of an organic film, the color or black matrixlayer being sandwiched between the first and second films.

[0141] The organic film of which the interlayer insulating film iscomposed prevents impurities contained in the color layer and/or theblack matrix layer from dissolving into the liquid crystal layer, andfurther prevents the first substrate from being influenced by movementof electric charges and/or ions in the color layer. This ensuresenhancement in reliability of the liquid crystal display device.

[0142] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an interlayerinsulating film formed between the data lines and the common electrode,the interlayer insulating film being comprised of a first film comprisedof an inorganic film, and a second film covering the first filmtherewith and comprised of an organic film, the color or black matrixlayer being sandwiched between the first and second films.

[0143] There is further provided an in-plane switching mode activematrix type liquid crystal display device includes (a) a firstsubstrate, (b) a second substrate located opposing the first substrate,and (c) a liquid crystal layer sandwiched between the first and secondsubstrates, wherein the first substrate includes (a 1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode, (a2) a pixel electrode each associated to a pixel to bedriven, (a3) a common electrode to which a reference voltage is applied,(a4) data lines, (a5) a scanning line, and (a6) common electrode lines,the gate electrode is electrically connected to the scanning line, thedrain electrode is electrically connected to the data lines, the sourceelectrode is electrically connected to the pixel electrode, and thecommon electrode is electrically connected to the common electrodelines, the pixel electrode is in a zigzag form and almost equally spacedaway from adjacent ones, the common electrode is in a zigzag form andalmost equally spaced away from adjacent ones, two-directional electricfields almost parallel with a surface of the first substrate are appliedacross the pixel electrode and the common electrode, the in-planeswitching mode active matrix type liquid crystal display device includesa first sub pixel area to which an electric field having a firstdirection is applied and in which molecular axes of liquid crystal inthe liquid crystal layer are rotated in a first rotational direction ina plane parallel with a surface of the first substrate, and a second subpixel area to which an electric field having a second direction isapplied and in which the molecular axes are rotated in a secondrotational direction which is different from the first rotationaldirection, in a plane parallel with a surface of the first substrate,the common electrode is composed of transparent material, and is formedon a layer located closer to the liquid crystal layer than the datalines, the common electrode entirely overlaps the data lines with aninsulating layer being sandwiched therebetween except an area where thedata lines are located in the vicinity of the scanning line, thein-plane switching mode active matrix type liquid crystal display devicefurther includes a light-impermeable layer in an area where the commonelectrode entirely overlaps the data lines, the light-impermeable layeris formed on the second substrate or on the first substrate such thatthe light-impermeable layer and the liquid crystal layer are located atthe same side with respect to the data lines and that thelight-impermeable layer faces the data lines, the light-impermeablelayer is comprised of a black matrix layer or multi-layered colorlayers, the black matrix layer or the multi-layered color layers has awidth smaller than a width of the common electrode overlapping the datalines, the data lines extends in a zigzag along the pixel electrode.

[0144] The above-mentioned in-plane switching mode active matrix typeliquid crystal display device can be obtained by applying the firstmentioned in-plane switching mode active matrix type liquid crystaldisplay device to a so-called multi-domain in-plane switching modeactive matrix type liquid crystal display device. The above-mentionedin-plane switching mode active matrix type liquid crystal display devicecan accomplish the above-mentioned first to third objects also in amulti-domain in-plane switching mode active matrix type liquid crystaldisplay device.

[0145] For instance, the data lines, the common electrode and the pixelelectrode are bent by one in each of pixels.

[0146] It would be possible to maximize an aperture ratio by setting thenumber of bent equal to one in the data lines, the common electrode andthe pixel electrode.

[0147] For instance, the data lines, the common electrode and the pixelelectrode are bent by an odd number equal to or greater than 3 in eachof pixels.

[0148] By setting the number of bent equal to an odd number, it would bepossible to equalize a region where liquid crystal molecules are twistedin a clockwise direction to a region where liquid crystal molecules aretwisted in a counter-clockwise direction in both an area and the number,ensuring enhancement in symmetry in a viewing angle.

[0149] It is preferable that the data lines, the common electrode andthe pixel electrode are bent by N in each of pixels, the N being definedin accordance with the equation (A):

30[μm]≦L/(N+1)[μm]≦40[μm]  (A)

[0150] wherein L indicates a length of an opening.

[0151] Smaller the number of bent in the data lines, the commonelectrode and the pixel electrode is, greater an aperture ratio is.However, bending patterns could be seen, if the number of bent is small.It is preferable that the black matrix layer is formed following bent ofthe data lines, the common electrode and the pixel electrode, but itwould be more difficult to pattern the black matrix layer, if the datalines, the common electrode and the pixel electrode are bent in asmaller number. In contrast, as the data lines, the common electrode andthe pixel electrode are bent in a greater number, a bending patternlooks like a line, and hence, the black matrix could be formed morelinear and thinner. However, greater the number of bent is, smaller anaperture ratio is. Taking these into consideration, the above-mentionedequation (A) provides the optimal number of bent in the data lines, thecommon electrode and the pixel electrode.

[0152] It is preferable that the black matrix layer facing the datalines is formed in a line.

[0153] It would be easiest to form the black matrix layer in a line.

[0154] As an alternative, the black matrix layer facing the data linesmay be formed in a zigzag, in which case, it is preferable that theblack matrix layer facing the data lines is bent in line with the datalines.

[0155] It would be possible to enhance an aperture ratio in the liquidcrystal display device by forming the black matrix layer in a zigzag inline with a zigzag shape of the data lines.

[0156] It is preferable that a distance along a substrate between one ofends of the black matrix layer facing the data lines and an end of thedata lines, located opposite to the one of ends of the black matrixlayer, is equal to or greater than 4 μm in a cross-section taken along aplane perpendicular to a direction in which the data lines extend.

[0157] By setting the above-mentioned distance equal to or greater than4 μm, it would be possible to prevent a leaked light obliquely coming atan end of the black matrix layer, from directly entering the data lines.

[0158] It is preferable that the black matrix layer is formed on thesecond substrate, and the black matrix layer facing the data linesoverlaps the data lines anywhere by 4 μm or greater, when viewed fromabove.

[0159] By designing the black matrix layer to overlap the data linesanywhere by 4 μm or greater, it would be possible to prevent a leakedlight obliquely coming at an end of the black matrix layer, fromdirectly entering the data lines.

[0160] It is preferable that the first or second substrate is comprisedfurther of a color layer formed in a line.

[0161] The color layer could be formed most easily in a line.

[0162] It is preferable that one of the first and second substrates iscomprised further of a color layer formed in a zigzag.

[0163] Though it might be slightly more difficult to form azigzag-shaped color layer than a linear color layer, a zigzag-shapedcolor layer matches in shape with a zigzag-shaped data line formed onthe first substrate, ensuring enhancement in a rate at which a light isused.

[0164] It is preferable that the color layer is bent in line with thedata lines.

[0165] By forming the color layer bent in line with the data lines, anaperture ratio could be increased.

[0166] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes a reverse-rotationpreventing structure in a sub pixel area in which all liquid crystalmolecules are rotated in the same direction, for preventing liquidcrystal molecules from rotating in a direction opposite to the samedirection. The reverse-rotation preventing structure includes anauxiliary electrode to which a voltage equal to a voltage of at leastone of the pixel electrode and the common electrode is applied such thatan initial alignment orientation of liquid crystal molecules overlaps adirection of an electric field generated in the sub pixel area in allsub-areas in the sub pixel areas, if the initial alignment orientationrotates by an acute angle.

[0167] It would be possible to stabilize alignment of liquid crystalmolecules and ensure clearer images to be displayed, by forming a pixelauxiliary electrode and a common auxiliary electrode between a sub pixelarea in which liquid crystal molecules are twisted in a clockwisedirection and a sub pixel area in which liquid crystal molecules aretwisted in a counter-clockwise direction. Both of the pixel auxiliaryelectrode and the common auxiliary electrode stabilize a boundary ofthose sub pixel areas.

[0168] It is preferable that the in-plane switching mode active matrixtype liquid crystal display device further includes an isolated floatingelectrode composed of a layer of which both the gate electrode and thedrain electrode are composed. The isolated floating electrode overlapsthe common or pixel electrode at bending portions of the zigzag-shapedcommon or pixel electrode with the insulating layer being sandwichedtherebetween, and has an extension extending in a direction in which thebending portions project, along an boundary between the first and secondsub pixel areas.

[0169] In an area in which the above-mentioned auxiliary electrode isdifficult to form, the formation of the isolated floating electrodewould make it possible to stably control domain. In general, when adisplay screen is pushed, there leaves a trace behind due to movement ofdomains. The formation of the isolated floating electrode prevents sucha trace from leaving behind, even if a display screen is pushed,ensuring stabilization of display.

[0170] It is preferable that the zigzag-shaped data lines include linearportions inclining towards the left and right from a direction in whichthe data lines extend.

[0171] It is preferable the black matrix layer is formed on the secondsubstrate, and the black matrix layer facing the data lines and formedin a line has a width greater anywhere than a minimum width Dmin definedby the following equation:

Dmin=D+LS×tan θ−(D−8)×2[μm]

[0172] wherein D indicates a width of the data lines, LS indicates alength obtained when the linear portions are projected towards thedirection in which the data lines extend, and θ indicates an angleformed between the direction in which the data lines extend and thelinear portions.

[0173] The above-mentioned equation makes it possible to theoreticallydefine a minimum width of the black matrix layer.

[0174] It is preferable the zigzag-shaped data lines includes firstlinear portions extending in parallel with a direction in which the datalines extend, and second linear portions inclining towards the left andright from the direction in which the data lines extend.

[0175] The first linear portions extending in parallel with a directionin which the data lines extend makes it possible to reduce a width ofthe black matrix layer necessary for preventing a light from obliquelyleaking, which light would be a problem when a linear black matrix layeris formed on the second substrate.

[0176] It is preferable the in-plane switching mode active matrix typeliquid crystal display device further includes coverages which are fitinto recessions formed at bending portions of the zigzag-shaped datalines.

[0177] Such coverages make it possible to reduce a width of the blackmatrix layer necessary for preventing a light from obliquely leaking,which light would be a problem when a linear black matrix layer isformed on the second substrate.

[0178] The in-plane switching mode active matrix type liquid crystaldisplay device may further include a floating light-impermeable filmcomposed of opaque metal, the floating light-impermeable filmoverlapping the data lines at recessions of bending portions of the datalines.

[0179] It is preferable the in-plane switching mode active matrix typeliquid crystal display device further includes a projection projectingfrom a bending portion of each of the zigzag-shaped common electrodeoverlapping the zigzag-shaped data lines.

[0180] When liquid crystal molecules are rotated in two directions byelectric fields generated between the common electrode overlapping thedata line and the pixel electrode located adjacent to the commonelectrode, the above-mentioned projection would stabilize domains at aboundary between regions in which liquid crystal molecules rotate in twodirections.

[0181] It is preferable that a storage capacity is formed between thepixel electrode comprised of the second metal layer of which the drainelectrode is formed, and the common electrode lines comprised of thefirst metal layer of which the gate electrode is formed.

[0182] This ensures that a storage capacity of the liquid crystal layeris increased, and images can be stably displayed.

[0183] There is still further provided an in-plane switching mode activematrix type liquid crystal display device includes (a) a firstsubstrate, (b) a second substrate located opposing the first substrate,and (c) a liquid crystal layer sandwiched between the first and secondsubstrates, wherein the first substrate includes (a1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode, (a2) a pixel electrode each associated to a pixel to bedriven, (a3) a common electrode to which a reference voltage is applied,(a4) data lines, (a5) a scanning line, and (a6) common electrode lines,the gate electrode is electrically connected to the scanning line, thedrain electrode is electrically connected to the data lines, the sourceelectrode is electrically connected to the pixel electrode, and thecommon electrode is electrically connected to the common electrodelines, the pixel electrode is in a zigzag form and almost equally spacedaway from adjacent ones, the common electrode is in a zigzag form andalmost equally spaced away from adjacent ones, two-directional electricfields almost parallel with a surface of the first substrate are appliedacross the pixel electrode and the common electrode, the in-planeswitching mode active matrix type liquid crystal display device includesa first sub pixel area to which an electric field having a firstdirection is applied and in which molecular axes of liquid crystal inthe liquid crystal layer are rotated in a first rotational direction ina plane parallel with a surface of the first substrate, and a second subpixel area to which an electric field having a second direction isapplied and in which the molecular axes are rotated in a secondrotational direction which is different from the first rotationaldirection, in a plane parallel with a surface of the first substrate, anopening of the first substrate extends in a direction perpendicular to adirection in which the data lines extend, the common electrode iscomposed of transparent material, and is formed on a layer locatedcloser to the liquid crystal layer than the data lines, the commonelectrode entirely overlaps the data lines with an insulating layerbeing sandwiched therebetween except an area where the data lines arelocated in the vicinity of the scanning line, the common electrode iselectrically connected to the common electrode lines through a contacthole in each of pixels, the in-plane switching mode active matrix typeliquid crystal display device further includes a light-impermeable layerin an area where the common electrode entirely overlaps the data lines,the light-impermeable layer is formed on the second substrate or on thefirst substrate such that the light-impermeable layer and the liquidcrystal layer are located at the same side with respect to the datalines and that the light-impermeable layer faces the data lines, thelight-impermeable layer is comprised of a black matrix layer ormulti-layered color layers, the black matrix layer or the multi-layeredcolor layers has a width smaller than a width of the common electrodeoverlapping the data lines, the data lines extend in a line, a gate linewhich constitutes the gate electrode extends in a zigzag.

[0184] In a liquid crystal display device where an opening of the firstsubstrate extends in a direction in which the data line extends, it ispreferable to pour liquid crystal into a space formed between the firstand second substrates, in a direction in which the data line extends. Incontrast, in a liquid crystal display device where an opening of thefirst substrate extends in a direction perpendicular to a direction inwhich the data line extends, such as the above-mentioned liquid crystaldisplay device, it is preferable to pour liquid crystal into a spaceformed between the first and second substrates, in a directionperpendicular to a direction in which the data line extends. Thus, itwould be possible to select a direction in which liquid crystal ispoured into a space, in dependence on a direction in which an opening ina liquid crystal display device extends.

[0185] There is yet further provided an in-plane switching mode activematrix type liquid crystal display device including (a) a firstsubstrate, (b) a second substrate located opposing the first substrate,and (c) a liquid crystal layer sandwiched between the first and secondsubstrates, wherein the first substrate includes (a1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode, (a2) a pixel electrode each associated to a pixel to bedriven, (a3) a common electrode to which a reference voltage is applied,(a4) data lines, (a5) a scanning line, and (a6) common electrode lines,the gate electrode is electrically connected to the scanning line, thedrain electrode is electrically connected to the data lines, the sourceelectrode is electrically connected to the pixel electrode, and thecommon electrode is electrically connected to the common electrodelines, the pixel electrode is in a zigzag form and almost equally spacedaway from adjacent ones, the common electrode is in a zigzag form andalmost equally spaced away from adjacent ones, two-directional electricfields almost parallel with a surface of the first substrate is appliedacross the pixel electrode and the common electrode, the in-planeswitching mode active matrix type liquid crystal display device includesa first sub pixel area to which an electric field having a firstdirection is applied and in which molecular axes of liquid crystal inthe liquid crystal layer are rotated in a first rotational direction ina plane parallel with a surface of the first substrate, and a second subpixel area to which an electric field having a second direction isapplied and in which the molecular axes are rotated in a secondrotational direction which is different from the first rotationaldirection, in a plane parallel with a surface of the first substrate, anisolated floating electrode formed of a layer of which the gateelectrode or the drain electrode is formed overlaps the common electrodeor the pixel electrode at bending portions of the zigzag-shaped commonor pixel electrode with an insulating film being sandwichedtherebetween, at least one of the common and pixel electrodes have aprojection projecting from bending portions of the zigzag-shaped commonand pixel electrodes in a direction in which the bending portionsproject, along a boundary between the first and second sub pixel areas.

[0186] In an area where the above-mentioned auxiliary electrode is hardto be formed, it would be possible to stabilize alignment of liquidcrystal molecules in the liquid crystal layer by forming the floatingelectrode.

[0187] In another aspect of the present invention, there is provided anelectronic device including one of the above-mentioned in-planeswitching mode active matrix type liquid crystal display devices.

[0188] By designing a liquid crystal display panel to include one of theabove-mentioned in-plane switching mode active matrix type liquidcrystal display devices, the liquid crystal display panel could have anincreased aperture ratio in a display area, ensuring enhancement in abrightness in the display area.

[0189] In still another aspect of the present invention, there isprovided a method of fabricating an in-plane switching mode activematrix type liquid crystal display device including (a) a firstsubstrate, (b) a second substrate located opposing the first substrate,and (c) a liquid crystal layer sandwiched between the first and secondsubstrates, wherein the first substrate includes (a1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode, (a2) a pixel electrode each associated to a pixel to bedriven, (a3) a common electrode to which a reference voltage is applied,(a4) data lines, (a5) a scanning line, (a6) common electrode lines, (a7)a data line terminal, (a8) a scanning line terminal, and (a9) a commonelectrode line terminal, the gate electrode is electrically connected tothe scanning line, the drain electrode is electrically connected to thedata lines, the source electrode is electrically connected to the pixelelectrode, and the common electrode is electrically connected to thecommon electrode lines, and molecular axes of liquid crystal in theliquid crystal layer are rotated in a plane parallel with the firstsubstrate by an electric field substantially parallel with a plane ofthe first substrate and to be applied between the pixel electrode andthe common electrode, to thereby display certain images, the methodincludes the steps of (a) forming the thin film transistor, the datalines, the scanning line and the common electrode line, and thereafter,forming an interlayer insulating film thereover, (b) etching theinterlayer insulating film to form contact holes reaching the datalines, the scanning line and the common electrode line, (c) deposittransparent metal all over a product resulted from the step (b) to coverinner surfaces of the contact holes with the transparent metal, therebyforming the data line terminal, the scanning line terminal and thecommon electrode line terminal, and (d) etching the transparent metal toform the common electrode such that the common electrode overlaps thedata lines.

[0190] It is preferable that the transparent metal is etched in the step(d) further for forming the pixel electrode.

[0191] It is preferable that the step (b) includes the step of forming asecond contact hole reaching the source electrode of the thin filmtransistor, and the step (c) includes the step of covering an innersurface of the second contact hole with the transparent metal.

[0192] It is preferable that the step (b) includes the step of forming athird contact hole reaching the common electrode lines, the step (c)includes the step of covering an inner surface of the third contact holewith the transparent metal, and the step (d) includes the step ofetching the transparent metal to electrically connect the commonelectrode to the third contact hole.

[0193] There is further provided a method of fabricating an in-planeswitching mode active matrix type liquid crystal display deviceincluding (a) a first substrate, (b) a second substrate located opposingthe first substrate, and (c) a liquid crystal layer sandwiched betweenthe first and second substrates, wherein the first substrate includes(a1) a thin film transistor having a gate electrode, a drain electrodeand a source electrode, (a2) a pixel electrode each associated to apixel to be driven, (a3) a common electrode to which a reference voltageis applied, (a4) data lines, (a5) a scanning line, and (a6) commonelectrode lines, the gate electrode is electrically connected to thescanning line, the drain electrode is electrically connected to the datalines, the source electrode is electrically connected to the pixelelectrode, and the common electrode is electrically connected to thecommon electrode lines, the pixel electrode is in a zigzag form andalmost equally spaced away from adjacent ones, the common electrode isin a zigzag form and almost equally spaced away from adjacent ones,two-directional electric fields almost parallel with a surface of thefirst substrate are applied across the pixel electrode and the commonelectrode, the in-plane switching mode active matrix type liquid crystaldisplay device includes a first sub pixel area to which an electricfield having a first direction is applied and in which molecular axes ofliquid crystal in the liquid crystal layer are rotated in a firstrotational direction in a plane parallel with a surface of the firstsubstrate, and a second sub pixel area to which an electric field havinga second direction is applied and in which the molecular axes arerotated in a second rotational direction which is different from thefirst rotational direction, in a plane parallel with a surface of thefirst substrate, the method includes the steps of (a) forming the thinfilm transistor, the data lines, the scanning line and the commonelectrode line, and thereafter, forming an interlayer insulating filmthereover, (b) etching the interlayer insulating film to form contactholes reaching the data lines, the scanning line and the commonelectrode line, (c) deposit transparent metal all over a productresulted from the step (b) to cover inner surfaces of the contact holeswith the transparent metal, thereby forming the data line terminal, thescanning line terminal and the common electrode line terminal, and (d)etching the transparent metal to form the common electrode such that thecommon electrode overlaps the data lines.

[0194] The advantages obtained by the aforementioned present inventionwill be described hereinbelow.

[0195] In accordance with the above-mentioned present invention, thefollowing objects of the present invention can be accomplished:

[0196] (a) to provide an in-plane switching mode liquid crystal displaydevice which is capable of preventing occurrence of vertical cross-talkwithout reduction in an aperture ratio;

[0197] (b) to reduce a resistance of common electrode in an in-planeswitching mode liquid crystal display device in which data lines arecovered with the common electrode composed transparent material;

[0198] (c) to reduce a light-impermeable film such as a black matrixlayer which was used in a conventional in-plane switching mode liquidcrystal display device for preventing vertical cross-talk caused by aleaking electric field, from appearing in a display screen while imagesare displayed in the display screen;

[0199] (d) to provide an in-plane switching mode liquid crystal displaydevice in which transparent electrodes can be fabricated with low costs;

[0200] (e) to provide an in-plane switching mode liquid crystal displaydevice in which a data line is almost entirely covered with a commonelectrode without an increase in a parasitic capacity to be formedbetween the data line and the common electrode; and

[0201] (f) to provide a reliable transparent material used for shieldinga data line therewith in an in-plane switching mode liquid crystaldisplay device.

[0202] In addition, the present invention can solve various problemsrelating to the above-mentioned matters.

[0203] It was found out in view of the results of the experiments havingbeen conducted by the inventors that the in-plane switching mode liquidcrystal display device in accordance with the later mentioned firstembodiment, for instance, could increase an aperture ratio by 30-40% incomparison with the conventional liquid crystal display deviceillustrated in FIG. 1.

[0204] The above and other objects and advantageous features of thepresent invention will be made apparent from the following descriptionmade with reference to the accompanying drawings, in which likereference characters designate the same or similar parts throughout thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0205]FIG. 1 is a partial cross-sectional view of a conventional liquidcrystal display device.

[0206]FIG. 2 is a partial cross-sectional view of the in-plane switchingmode liquid crystal display device in accordance with the presentinvention.

[0207]FIG. 3 is a graph showing the results of simulation for showingthe function of shielding a leaking electric field, obtained by thein-plane switching mode liquid crystal display device in accordance withthe present invention.

[0208]FIG. 4 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the first embodiment of thepresent invention.

[0209]FIG. 5 is a cross-sectional view taken along the line V-V in FIG.4.

[0210]FIG. 6 is a circuit diagram of a unit pixel in the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0211]FIG. 7 is a partial plan view of a variant of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0212]FIG. 8 is a cross-sectional view taken along the lines A-A, B-Band C-C in the in-plane switching mode liquid crystal display deviceillustrated in FIG. 10 wherein the second interlayer insulating film hasa multi-layered structure.

[0213]FIG. 9 is a cross-sectional view taken along the lines A-A, B-Band C-C in the in-plane switching mode liquid crystal display deviceillustrated in FIG. 10 wherein the second interlayer insulating film hasa single-layered structure.

[0214]FIG. 10 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the first embodiment, used forexplaining the method of fabricating the same.

[0215]FIG. 11 is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, showing a relation between a width of the data lineand a width of the common electrode.

[0216]FIG. 12 is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, showing a relation between a width of the data lineand a width of the black matrix layer.

[0217]FIG. 13 is a plan view showing an area in which the black matrixlayer is to be formed on the second substrate in the in-plane switchingmode liquid crystal display device illustrated in FIG. 4.

[0218]FIG. 14 is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, showing an advantage of the common electrode beingcomposed of ITO.

[0219]FIG. 15 is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, showing a relation between an extended width of thecommon electrode and the data line.

[0220]FIG. 16 is a graph showing the results of simulation relating to alight leaking at a side of the data line.

[0221]FIG. 17 is a partial cross-sectional view of a variant of thein-plane switching mode liquid crystal display device in accordance withthe first embodiment.

[0222]FIG. 18 is a partial cross-sectional view of another variant ofthe in-plane switching mode liquid crystal display device in accordancewith the first embodiment.

[0223]FIG. 19A is a plan view illustrating only the first and secondmetal layers in the in-plane switching mode liquid crystal displaydevice illustrated in FIG. 18.

[0224]FIG. 19B is a plan view illustrating only the layers composed ofITO, in the in-plane switching mode liquid crystal display deviceillustrated in FIG. 18.

[0225]FIG. 20 is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, used for explaining the advantage obtained by forminga passivation film on the common electrode.

[0226]FIG. 21 is a partial cross-sectional view of an in-plane switchingmode liquid crystal display device, used for explaining the problemcaused when a passivation film is not formed on a common electrode.

[0227]FIG. 22 is a partial cross-sectional view of still another variantof the in-plane switching mode liquid crystal display device inaccordance with the first embodiment.

[0228]FIG. 23 is a partial cross-sectional view of yet another variantof the in-plane switching mode liquid crystal display device inaccordance with the first embodiment.

[0229]FIG. 24 is a partial plan view of another variant of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0230]FIG. 25 is a partial plan view of another variant of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0231]FIG. 26 is a partial plan view of another variant of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0232]FIG. 27 is a partial plan view of another variant of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0233]FIGS. 28A to 28K are cross-sectional views of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, illustrating respective steps in a first example ofthe method of fabricating the same.

[0234]FIGS. 29A to 29I are cross-sectional views of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, illustrating respective steps in a second example ofthe method of fabricating the same.

[0235]FIGS. 30A to 30I are cross-sectional views of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, illustrating respective steps in a third example ofthe method of fabricating the same.

[0236]FIG. 31 is a plan view illustrating an arrangement of the scanningline, the data line and the common electrode line in the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment.

[0237]FIG. 32 is a plan view illustrating an arrangement of the scanningline terminal, the data line terminal and the common electrode lineterminal in the in-plane switching mode liquid crystal display device inaccordance with the first embodiment.

[0238]FIGS. 33A to 33J are cross-sectional views of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, illustrating respective steps in a first example ofthe method of fabricating the in-plane switching mode liquid crystaldisplay device together with the terminals.

[0239]FIGS. 34A to 34I are cross-sectional views of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, illustrating respective steps in a second example ofthe method of fabricating the in-plane switching mode liquid crystaldisplay device together with the terminals.

[0240]FIGS. 35A to 35H are cross-sectional views of the in-planeswitching mode liquid crystal display device in accordance with thefirst embodiment, illustrating respective steps in a third example ofthe method of fabricating the in-plane switching mode liquid crystaldisplay device together with the terminals.

[0241]FIG. 36 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the second embodiment of thepresent invention.

[0242]FIG. 37 is a cross-sectional view taken along the line XXX VII-XXXVII in FIG. 36.

[0243]FIG. 38 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the third embodiment of thepresent invention.

[0244]FIG. 39 is a cross-sectional view taken along the line XXX IX-XXXIX in FIG. 38.

[0245]FIG. 40 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the fourth embodiment of thepresent invention.

[0246]FIG. 41 is a cross-sectional view taken along the line XXXX I-XXXXI in FIG. 40.

[0247]FIG. 42A shows a direction in which an opening extends.

[0248]FIG. 42B shows another direction in which an opening extends.

[0249]FIG. 43A is a plan view illustrating a first example of a zigzagline.

[0250]FIG. 43B is a plan view illustrating a second example of a zigzagline.

[0251]FIG. 44 is a plan view of a conventional liquid crystal displaydevice, used for explaining an increase in an aperture ratio in thein-plane switching mode liquid crystal display device in accordance withthe fourth embodiment.

[0252]FIG. 45 is a cross-sectional view taken along the line XXXX V-XXXXV in FIG. 44.

[0253]FIG. 46 is a plan view of a conventional liquid crystal displaydevice, used for explaining an increase in an aperture ratio in thein-plane switching mode liquid crystal display device in accordance withthe fourth embodiment.

[0254]FIG. 47 is a cross-sectional view taken along the line XXXXVI-XXXX VI in FIG. 46.

[0255]FIG. 48 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the fourth embodiment, showingan increase in an aperture ratio in the same.

[0256]FIG. 49 is a cross-sectional view taken along the line XXXXIX-XXXX IX in FIG. 48.

[0257]FIG. 50 is a partial cross-sectional view of a variant of thein-plane switching mode liquid crystal display device in accordance withthe fourth embodiment.

[0258]FIG. 51 is a plan view of a first example of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0259]FIG. 52 is a plan view of a second example of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0260]FIG. 53 is a plan view of a minimum width of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0261]FIG. 54 is a plan view of a third example of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0262]FIG. 55 is a plan view of a fourth example of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0263]FIG. 56 is a plan view of a fifth example of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0264]FIG. 57 is a plan view of a sixth example of the black matrixlayer in the in-plane switching mode liquid crystal display device inaccordance with the fourth embodiment.

[0265]FIG. 58 is a partial plan view of another variant of the in-planeswitching mode liquid crystal display device in accordance with thefourth embodiment.

[0266]FIG. 59 is a partial plan view of still another variant of thein-plane switching mode liquid crystal display device in accordance withthe fourth embodiment.

[0267]FIG. 60 is a partial plan view of yet another variant of thein-plane switching mode liquid crystal display device in accordance withthe fourth embodiment, to which the floating electrode illustrated inFIG. 59 is applied.

[0268]FIG. 61 is a cross-sectional view taken along the lines A-A, B-Band C-C in FIG. 60, illustrating the TFT part, the unit pixel part andthe contact hole part in the unit pixel part in the in-plane switchingmode liquid crystal display device in accordance with the fourthembodiment.

[0269]FIG. 62A is a plan view of the transparent electrodes illustratedin FIG. 60.

[0270]FIG. 62B is a plan view of the electrodes other than thetransparent electrodes illustrated in FIG. 60.

[0271]FIG. 63A is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thefifth embodiment.

[0272]FIG. 63B is a partial cross-sectional view of the in-planeswitching mode liquid crystal display device in accordance with thesixth embodiment.

[0273]FIG. 64 is a plan view of the in-plane switching mode liquidcrystal display device in accordance with the eighth embodiment of thepresent invention.

[0274]FIG. 65 is a cross-sectional view taken along the line XXXXXXV-XXXXXX V in FIG. 64.

[0275]FIG. 66 is a block diagram of a first example of an electronicdevice to which the in-plane switching mode liquid crystal displaydevice in accordance with one of the first to sixth embodiments isapplied.

[0276]FIG. 67 is a block diagram of a second example of an electronicdevice to which the in-plane switching mode liquid crystal displaydevice in accordance with one of the first to sixth embodiments isapplied.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0277] Preferred embodiments in accordance with the present inventionwill be explained hereinbelow with reference to drawings.

[0278] [First Embodiment]FIGS. 4, 5 and 6 illustrate an in-planeswitching mode active matrix type liquid crystal display device inaccordance with the first embodiment of the present invention. FIG. 4 isa plan view of the liquid crystal display device 10 in accordance withthe first embodiment, FIG. 5 is a cross-sectional view taken along theline V-V in FIG. 4, and FIG. 6 is a circuit diagram of a unit pixel.

[0279] As illustrated in FIG. 5, the liquid crystal display device 10 iscomprised of an active device substrate 11, an opposing substrate 12,and a liquid crystal layer 13 sandwiched between the active devicesubstrate 11 and the opposing substrate 12.

[0280] The opposing substrate 12 includes an electrically insulatingtransparent substrate 16, a black matrix layer 17 formed on a firstsurface of the electrically insulating transparent substrate 16 as alight-impermeable film, a color layer 18 formed on the first surface ofthe electrically insulating transparent substrate 16 such that the colorlayer 18 partially overlaps the black matrix layer 17, and a transparentovercoating layer 19 covering the black matrix layer 17 and the colorlayer 18 therewith.

[0281] The color layer 18 is comprised of resin films containing red(R), green (G) and blue (B) pigments.

[0282] The opposing substrate 12 further includes an electricallyconductive transparent layer 15 on a second surface of the electricallyinsulating transparent substrate 16 in order to prevent electric chargescaused by contact of a liquid crystal display panel with othermaterials, from exerting electrical influence on the liquid crystallayer 13.

[0283] The active matrix substrate 11 includes an electricallyinsulating transparent substrate 22, a first metal layer formed on theelectrically insulating transparent substrate 22 and defining a scanningline 28 (see FIG. 4) and a gate electrode 30 c (see FIG. 6) therein, afirst interlayer insulating film 23 formed on the electricallyinsulating transparent substrate 22, an island-shaped amorphous siliconfilm formed on the first interlayer insulating film 23, a second metallayer defining a data line 24, and a source electrode 30 b and a drainelectrode 30 a of a thin film transistor 30 therein, a first film 25 aformed on the first interlayer insulating film 23, a second film 25 bformed on the first film 25 a, and a common electrode 26 and a pixelelectrode 27 formed as transparent electrodes on the second film 25 b.

[0284] The first and second films 25 a and 25 b constitute a secondelectrically insulating film 25.

[0285] The active matrix substrate 11 further includes a pixel auxiliaryelectrode 35 formed on the first interlayer insulating film 23 togetherwith the data lines 24 (see FIG. 8). The data lines 24 and the pixelauxiliary electrode 35 are composed of the second metal layer.

[0286] In the specification, an “upper” layer means a layer locatedcloser to the liquid crystal layer 13, and a “lower” layer means a layerlocated remoter from the liquid crystal layer 13 in both the activedevice substrate 11 and the opposing substrate 12.

[0287] The active device substrate 11 and the opposing substrate 12include alignment films 31 and 32, respectively, both making contactwith the liquid crystal layer 13. As illustrated in FIG. 4, thealignment films 31 and 32 are rubbed such that the liquid crystal layer13 is homogeneously aligned in a direction inclined from a direction inwhich the common electrode 27 and the pixel electrode 26 extend, by anangle in the range of 10 to 30 degrees, and then, adhered to the activedevice substrate 11 and the opposing substrate 12, respectively, suchthat they face each other. The above-mentioned angle is called initialalignment orientation of liquid crystal molecules.

[0288] Though not illustrated, spacers are sandwiched between the activedevice substrate 11 and the opposing substrate 12 to ensure a thicknessof the liquid crystal layer 13, and a seal is formed around the liquidcrystal layer 13 between the active device substrate 11 and the opposingsubstrate 12 for avoiding leakage of liquid crystal molecules.

[0289] The active device substrate 11 further includes a polarizingplate 21 formed on a lower surface of the electrically insulatingtransparent substrate 22, and similarly, the opposing substrate 12includes a polarizing plate 14 formed on the electrically conductivelayer 15. The polarizing plate 21 of the active device substrate 11 hasa polarization axis extending perpendicularly to the liquid crystalinitial alignment direction, and the polarizing plate 14 of the opposingsubstrate 12 has a polarization axis extending in parallel to the liquidcrystal initial alignment direction. The polarization axes extendperpendicularly to each other.

[0290] As illustrated in FIG. 4, the active device substrate 11 includesdata lines 24 to which data signals are transmitted, common electrodelines 26 a and 26 b to which a reference voltage is applied, a commonelectrode 26 to which the reference voltage is applied, a pixelelectrode 27 associated with pixels in which images are to be displayed,a scanning line 28 to which a scanning signal is applied, and a thinfilm transistor (TFT) 30.

[0291] The thin film transistor 30 includes a gate electrode 30 c (seeFIG. 8), a drain electrode 30 a, and a source electrode 30 b. The thinfilm transistor 30 is located in the vicinity of an intersection of thescanning line 28 and the data line 24 in association with a pixel. Thegate electrode 30 c is electrically connected to the scanning line 28,the drain electrode 30 a is electrically connected to the data line 24,and the source electrode 30 b is electrically connected to the pixelelectrode 27.

[0292] Both the common electrode 26 and the pixel electrode 27 aredesigned to have a comb-teeth shape, and the comb-teeth in the commonelectrode 26 and the pixel electrode 27 extend in parallel with the datalines 24. The comb-teeth of the common electrode 26 and the comb-teethof the pixel electrode 27 are arranged to be in mesh with each other,and further spaced away from each other.

[0293] As illustrated in FIG. 4, the common electrode 26 formed astransparent electrodes are electrically connected to the commonelectrode line 26 b through a contact hole 39 a.

[0294]FIG. 7 separately illustrates layer (B) defining a transparentelectrode of which the common and pixel electrodes 26 and 27 arecomposed, and layers (A) other than the above-mentioned layer (B), amongthe layers in the liquid crystal display device 10 illustrated in FIG.4. In view of FIG. 7, it is understood that no light-impermeable filmsexist between the common electrode 26 overlapping the data lines 24 andthe pixel electrode 27 located adjacent to the common electrode 26, whenviewed on a plan view.

[0295]FIGS. 8 and 9 illustrate a TFT device part, a unit pixel part, anda contact hole part of the unit pixel part in the in-plane switchingmode liquid crystal display device 10. The TFT device part, the unitpixel part, and the contact hole part are illustrated as cross-sectionalviews taken along the lines A-A, B-B and C-C in FIG. 10.

[0296] In FIG. 8, the second interlayer insulating film 25 is designedto have a multi-layered structure of the first film 25 a and the secondfilm 25 b, whereas in FIG. 9, the second interlayer insulating film 25is designed to have a single-layered structure of the first film 25 a.Explanation is made hereinbelow with reference to FIG. 8. When thesecond interlayer insulating film 25 has a single-layered structure, thefirst film 25 a may be considered as a lower layer in the secondinterlayer insulating film, and the second film 25 b may be consideredas an upper layer in the second interlayer insulating film.

[0297] As illustrated in FIGS. 8 and 4, the common electrode lines 26 aand 26 b are comprised of the first metal layer, extend in parallel withthe scanning lines 28, and are applied a voltage of the common electrode26 thereto at a periphery thereof.

[0298] As illustrated in FIG. 4, the pixel electrode 27 comprised of atransparent electrode is electrically connected to the pixel auxiliaryelectrode 35 through a contact hole 39 b. The pixel auxiliary electrode35 is comprised of the second metal layer, and is formed integral withthe source electrode 30 b of the thin film transistor 30.

[0299] In the in-plane switching mode active matrix type liquid crystaldisplay device 10 in accordance with the first embodiment, in a pixelwhich is selected in accordance with a scanning signal transmittedthrough the scanning line 28, and to which a data signal transmittedthrough the data line 24 is written, an electric field is generated inparallel with the transparent substrates 16 and 22 between the commonelectrode 26 and the pixel electrode 27, and alignment orientation ofliquid crystal molecules in the liquid crystal layer 13 is rotated inaccordance with the electric field in a plane parallel with thetransparent substrates 16 and 22, to thereby display images on a displayscreen of the liquid crystal display device 10. In FIG. 4, a verticallylong area surrounded by the common electrode 26 and the pixel electrode27 is called a column. In the in-plane switching mode active matrix typeliquid crystal display device 10, both the common electrode 26 and thepixel electrode 27 are composed of indium-tin-oxide (ITO) which istransparent material.

[0300] As illustrated in FIGS. 7 and 8, the in-plane switching modeactive matrix type liquid crystal display device 10 may be designed toinclude the pixel auxiliary electrode 35 below the second interlayerinsulating film 25. The pixel auxiliary electrode 35 is formed integralwith the source electrode 30 b of the thin film transistor 30 formed ofthe second metal layer formed on the first interlayer insulating film23.

[0301] As illustrated in FIG. 7, the pixel auxiliary electrode 35 iscomprised of a first portion 35 a overlapping the common electrode line26 b formed of the first metal layer and defining a storage capacitytogether with the common electrode line 26 b, a second portion 35 boverlapping the common electrode line 26 a formed of the first metallayer and defining a storage capacity together with the common electrodeline 26 a, and a third portion 35 c extending in parallel with the datalines 24, being formed below the pixel electrode 27 formed above thesecond interlayer insulating film 25, and connecting the first andsecond portions 35 a and 35 b to each other. The pixel auxiliaryelectrode 35 is in the form of “I”.

[0302] The first to third portions 35 a, 35 b and 35 c of the pixelauxiliary electrode 35 are formed of the opaque second metal layer onthe first interlayer insulating film 23. As will be understood in viewof FIG. 8, the drain electrode 30 a and the source electrode 30 b of thethin film transistor 30 are formed also of the opaque second metallayer. The source electrode 30 b is electrically connected to the pixelauxiliary electrode 35.

[0303] Though light transmissivity is slightly reduced if the pixelauxiliary electrode 35 is composed of opaque metal, it would be possibleto form storage capacity at both upper and lower sides when viewed in aplan view of a pixel, by electrically connecting the first to thirdportions 35 a, 35 b and 35 c to one another, ensuring an increase instorage capacity and stabilization in displaying images.

[0304] It should be noted that a shape of the pixel auxiliary electrode35 is not to be limited to “I” illustrated in FIG. 7. The pixelauxiliary electrode 35 may be designed to have any shape, unless it islocated below the pixel electrode 27.

[0305] Though not illustrated in FIG. 7, a common auxiliary electrodemay be formed of the second metal layer on the first interlayerinsulating film 23, and be electrically connected to the commonelectrode lines 26 a and 26 b both formed of the first metal layer, andthe common electrode 26.

[0306] As illustrated in FIG. 8, the gate electrode 30 c of the thinfilm transistor 30 is formed of the first metal layer.

[0307] It would be possible to form storage capacity at both upper andlower sides when viewed in a plan view of a pixel, by electricallyconnecting the common electrodes 26 to each other, ensuring an increasein storage capacity and stabilization in displaying images.

[0308] As illustrated in FIGS. 4 and 5, the common electrode 26 isformed on a layer located upper than the data lines 24, and entirelyoverlaps the data lines 24 except both an area in which the data line 24intersects with the scanning line 28 and a region around the area.

[0309] Specifically, as illustrated in FIG. 11, assuming that L(D)indicates a width of the data line 24, and L(COM) indicates a width ofthe common electrode 26, L(COM) is greater than L(D), and in addition,the width L(D) of the data line 24 is entirely covered by the widthL(COM) of the common electrode 26.

[0310] L(COM)>L(D)

[0311] In FIG. 4, since there is formed a high step in an area in whichthe data line 24 intersects with the scanning line 28 and a regionaround the area, the common electrode 26 does not overlap the data line24 in the area and region in order to avoid short-circuit.

[0312] As mentioned earlier, the black matrix layer 17 formed above thedata line 24 is designed to have a smaller width than a width of thecommon electrode 26, and there does not exist a light-impermeable filmbetween the common electrode 26 overlapping the data line 24 and thepixel electrode 27 formed adjacent to the common electrode 26, in a topplan view. In addition, the black matrix layer 17 is designed to have asmaller width than a width of the data line 24, and overlap the dataline 24 in its entirety.

[0313] That is, as illustrated in FIG. 12, assuming that L(D) indicatesa width of the data line 24, and L(BM) indicates a width of the blackmatrix layer 17, the width L(D) is greater than L(BM), and the L(BM) isentirely overlapped by the width L(D).

[0314] L(D)>L(BM)

[0315] By designing the black matrix layer 17 to have a smaller widththan a width of the data line 24, it would be possible to make use of alight passing through extensions of the transparent common electrode 26which extend beyond the data line 24, ensuring enhancement intransmissivity of a light through a panel.

[0316] The black matrix layer 17 in the first embodiment is designed tohave a width of 6 μm. However, it should be noted that a width of theblack matrix layer 17 is not to be limited to 6 μm. The black matrixlayer 17 may be designed to have a width greater than 6 μm as well as 6μm. If the black matrix layer 17 had a width smaller than 6 μm, muchlight would be reflected at the data line 24, resulting in that imagesdisplayed on a screen of the liquid crystal display device 10 would bequite difficult to see in bright environment.

[0317] The common electrode 26 may be composed of the same material as amaterial of which a layer covering the terminals of the liquid crystaldisplay device 10 therewith is composed. Specifically, the commonelectrode line terminal may be composed of an ITO layer of which thecommon electrode 26 is composed, like the contact hole 39 a illustratedin FIG. 8. Similarly, both the scanning line terminal and the data lineterminal may be composed of the ITO layer of which the common electrode26 is composed.

[0318] As a result, the common electrode 26 can be formed concurrentlywith the terminals of the liquid crystal display device 10 and becomposed of a material of which the terminals are composed. This ensuresprevention of an increase in the number of steps for forming the commonelectrode 26.

[0319] In the liquid crystal display device 10, if the common electrode26 does not completely overlap the data line 24, the common electrode 26would not shield an electric field associated with the data line 24. Asa result, there will be generated an electric field between the commonelectrode 26 and the pixel electrode 27, causing malfunction of liquidcrystal molecules. Specifically, liquid crystal molecules do not behavein accordance with a voltage difference between the common electrode 26and the pixel electrode 27, causing vertical cross-talk.

[0320] If the opposing substrate 12 were designed to have the blackmatrix layer 17 and the black matrix layer 17 had a sufficiently greatwidth, an area where malfunction of liquid crystal molecules occurs maybe shielded from a viewer. In contrast, if the black matrix layer 17does not overlap the data line 24, such an area where malfunction ofliquid crystal molecules occurs can be shielded from a viewer by forminga light-impermeable layer electrically connected to the common electrode26, below the data line 24, to thereby shield a light emitted from aback-light device. If the light-impermeable layer were not electricallyconnected to the common electrode 26, the light-impermeable layer wouldhave an unstable voltage, resulting in that a DC electric field isgenerated between the common electrode 26 and the pixel electrode 27, ormalfunction such as cross-talk occurs.

[0321] Specifically, such a light-impermeable layer as mentioned aboveis comprised of the first metal layer of which the scanning line 28 iscomprised, and electrically connected to the common electrode line 26 a.Since the common electrode lines 26 a and 26 b are electricallyconnected to the common electrode 26 through the contact hole 39 a, thecommon electrode lines 26 a and 26 b may be used as a light-impermeablelayer.

[0322] The above-mentioned light-impermeable layer may be formed as asingle layer composed of chromium, titanium, molybdenum, tungsten oraluminum, or may be designed to have a multi-layered structure includinglayers composed of those metals. A light-impermeable layer having amulti-layered structure would have a reduced resistance.

[0323] With reference to FIG. 4, the common electrode 26 does notoverlap the data lines 24 at intersections of the data lines 24 and thescanning line 28 and regions therearound. Accordingly, the commonelectrode 26 cannot shield an electric field derived from the data lines24 at the intersections of the data lines 24 and the scanning line 28.As a result, there would be generated an electric field at theintersections and regions therearound, and liquid crystal molecules inthe liquid crystal layer 13 would behave improperly. In addition, liquidcrystal molecules would behave improperly due to an electric fieldderived from the data lines 28.

[0324] However, since the common electrode lines 26 a and 26 b arecomprised of the first metal layer of which the scanning line is alsocomprised, it would be impossible for the common electrode lines 26 aand 26 b to shield the above-mentioned intersections and regionstherearound where liquid crystal molecules would behave improperly.

[0325] Hence, it is preferable that those intersections and regions areshielded with the black matrix layer 17.

[0326]FIG. 13 illustrates an example where the black matrix layer 17shields the intersections and regions. As illustrated in FIG. 13, theblack matrix layer 17 formed in an area surrounded by a thick solid linecovers the scanning line 28, regions therearound, spaces between thescanning line 28 and the pixel electrode 27, and regions therearoundtherewith to thereby shield them from a light.

[0327] The common electrode 26 in the liquid crystal display device 10in accordance with the first embodiment is composed of ITO which is oneof transparent materials. This ensures an increase in a transparent areain the liquid crystal display device 10 with the result of an increasein an aperture ratio in the liquid crystal display device 10.

[0328] Though an ITO film has a rather high sheet resistance,specifically about 100 ohms per a unit area, it would be possible toreduce a resistance in the common electrode 26 in its entirety and topresent redundancy to the common electrode 26 by electrically connectingthe ITO film to the common electrode line 26 a or 26 b in each ofpixels, and horizontally electrically connecting the common electrode26, which is comprised of the ITO film, to each other.

[0329] As is understood in view of FIG. 5, the second interlayerinsulating film 25 is sandwiched between the common electrode 26 and thedata line 24. By designing the second interlayer insulating film 25 tohave a high ratio d/ε wherein “d” indicates a thickness of the secondinterlayer insulating film 25 and “ε” indicates a dielectric constant,it would be possible to reduce a parasitic capacitance to be formedbetween the data lines 24 and the common electrode 26.

[0330] In addition, since the above-mentioned cross-talk problem issolved, it would be no longer necessary to form the black matrix layer17 for the purpose of preventing degradation in displaying images,caused by an electric field leaking out of the data lines 24.Accordingly, the black matrix layer 17 may be formed only forimprovement in contrast, ensuring that the black matrix layer 17 couldhave a reduced width. Reduction in a width of the black matrix layer 17would ensure an increase in an aperture ratio in the liquid crystaldisplay device 10.

[0331] In the liquid crystal display device 10, both the commonelectrode 26 and the pixel electrode 17 are formed on the secondinterlayer insulating film 25. By forming both the common electrode 26and the pixel electrode 27 in a common layer, it would be possible toform the common electrode 26 and the pixel electrode 27 in the same stepand compose them of the same material, ensuring enhancement in afabrication yield.

[0332] As mentioned earlier, the common electrode 26 shielding the datalines 24 is composed of ITO in the liquid crystal display device 10. Bycomposing the common electrode 26 of ITO, it would be possible toenhance reliability of the liquid crystal display device 10 incomparison with cases where the common electrode 26 is composed ofmetals other than ITO. The reason therefor is explained hereinbelow.

[0333] As illustrated in FIG. 14, it is assumed that the commonelectrode 26 and the pixel electrode 27 both composed of a metal otherthan ITO are formed on the second interlayer insulating film 25, and analignment film 31 having a thickness in the range of 500 to 1000angstroms is formed on the second interlayer insulating film 25,covering the common electrode 26 and the pixel electrode 27 therewith.

[0334] If the alignment film 31 had a pin-hole 32, liquid crystalmaterial of which the liquid crystal layer 13 is composed and the metalof which the common electrode 26 and the pixel electrode 27 are composedwould electrochemically react with each other, resulting in that themetal of which the common electrode 26 and the pixel electrode 27 arecomposed might be eluted into the liquid crystal layer 13 as metal ions33. Such elution of the metal ions 33 into the liquid crystal layer 13would cause non-uniformity in displaying images.

[0335] In particular, when the liquid crystal layer 13 is composed ofliquid crystal material having intensive polarity, the metal ions 33would be eluted into the liquid crystal layer 13 more aggressively.Since it is necessary in an in-plane switching mode liquid crystaldisplay device to form the liquid crystal layer 13 of a material havinga high dielectric constant anisotropy Δε, the metal ions 33 would beaggressively eluted into the liquid crystal layer 13.

[0336] Accordingly, the common electrode 26 and the pixel electrode 27both making contact with the alignment film 31 are preferably composedof a material which is unlikely to electrochemically react with liquidcrystal material, that is, a material which is less reactive with liquidcrystal material.

[0337] As is obvious in view of the fact that a transparent electrode ina TN (Twisted Nematic) or STN (Super Twisted Nematic) type liquidcrystal display device is frequently composed of ITO, ITO is quitestable to electrochemical reaction such as the above-mentioned one.

[0338] Hence, the common electrode 26 and the pixel electrode 27 bothcomposed of ITO can be formed making direct contact with the alignmentfilm 31, ensuring enhancement in reliability in the liquid crystaldisplay device 10 in comparison with liquid crystal display devicesincluding a common electrode and a pixel electrode both composed of ametal other than ITO.

[0339] Hereinbelow is explained the liquid crystal display device 10 inaccordance with the first embodiment in detail. In addition, variants ofthe liquid crystal display device 10 will be explained hereinbelow.

[0340] In the liquid crystal display device 10, the common electrode 26is entirely overlapped by the data lines 24 in almost all regions of theliquid crystal display device 10. It is preferable that the commonelectrode 26 has extensions extending beyond the data line 24 in awidth-wise direction at opposite sides thereof by 1.5 μm or greater.

[0341] The inventors had conducted the experiment to find a relationamong a length Le [μm] of extensions cf the common electrode 26extending beyond edges of the data line 24 in a width-wise directionthereof, a thickness “d” of the second interlayer insulating film 25,and light passage passing at the side of the data line 24.

[0342]FIG. 15 is a cross-sectional view of the liquid crystal displaydevice to which the inventors had conducted the experiment. Theconditions in the experiment were as follows.

[0343] Dielectric constant anisotropy of liquid crystal Δε·=8

[0344] Index of refraction of liquid crystal=0.067

[0345] Thickness of the liquid crystal layer 13=4.5 μm

[0346] Light transmissivity of the common electrode 26=100%(transparent)

[0347] Light transmissivity of the data line 24=0% (opaque)

[0348] Distance between the common electrode 26 and the pixel electrode27=10 μm

[0349] Dielectric constant of the second interlayer insulating film 25:ε=3

[0350] Thickness “d” of the second interlayer insulating film 25=0.5,1.0, and 2.0 μm

[0351] Under the above-mentioned conditions, there was conducted theexperiment in which a screen in which a white window was displayed withblack background was displayed in black. FIG. 16 shows light passage inthe experiment, caused by an electric field leaking out of the data line24 due to white-display in surroundings. Light passage in FIG. 16 wascalculated by integrating light transmissivity over a width associatedwith a pixel, illustrated in FIG. 15.

[0352] Though light transmissivity in black-display is equal to 0.0, ithas a certain value due to an electric field leaking out of the dataline 24. As illustrated in FIG. 16, the greater the extension Le [μm]is, the smaller the light passage is. This is not dependent on thethickness “d” of the second interlayer insulating film 25.

[0353] On the other hand, the light passage in white-display iscalculated by integrating the light transmissivity in white-display overa width associated with a pixel. Specifically, the light passage inwhite-display is calculated equal to 12. It is necessary for the maximumallowable light passage passing at the side of the data line 24 to beequal to or smaller than {fraction (1/100)} of light passage in a pixelobtained when white is displayed in a screen. Hence, the light passagehas to be equal to or smaller than 0.12 in FIG. 16.

[0354] In FIG. 16, the extension Le [μm] of the common electrode 26 canbe read as about 1.5 mm when the light passage is equal to 0.12.Accordingly, it would be possible to lower the maximum allowable lightpassage passing at the side of the data line 24, by determining theextension Le [μm] of the common electrode 26 to be equal to 1.5 μm.

[0355] In the first embodiment, the liquid crystal display device 10 isdesigned to include the black matrix layer 17 separately from the colorlayer 18. However, it should be noted that the black matrix layer 17might be replaced with a multi-layered structure of a plurality of thecolor layers 18.

[0356] With reference to FIG. 17, a red layer 18 a, a green layer 18 band a blue layer 18 c are designed to partially overlap one another.Portions of the color layers 18 a to 18 c at which the color layers 18 ato 18 c partially overlap one another have the same function of theblack matrix layer 17.

[0357] It would be no longer necessary to form the black matrix layer 17by designing the color layers 18 a to 18 c to partially overlap oneanother. The red, green and blue layers 18 a to 18 c may be formed suchthat they overlap one another, by changing patterns of the color layers18 a to 18 c. Since work volume for changing patterns of the colorlayers 18 a to 18 c is smaller than work volume for forming the blackmatrix layer 17, the multi-layered structure of the color layers 18 a to18 c would enhance a fabrication yield of the liquid crystal displaydevice 10.

[0358] In place of layering three color layers as mentioned above, anytwo color layers among red, green and blue layers may be layered one onanother to substitute for the black matrix layer 17.

[0359] In the liquid crystal display device 10, the pixel auxiliaryelectrode 35, the common electrode line 26 a and the common electrodeline 26 b which define upper and lower ends in each of columns in adirection in which the data line 24 extends may be designed to have suchoblique edges as illustrated in FIG. 18 such that a relation among arubbing direction or a liquid crystal alignment direction defined byrubbing and a direction of an electric field applied across the pixelelectrode 27 (and the pixel auxiliary electrode 35 to which the samevoltage as that of the pixel electrode 27 is applied) and the commonelectrode 26 (and the common electrode lines 26 a and 26 b to which thesame voltage as that of the common electrode 26 is applied) isdetermined to ensure that the liquid crystal alignment direction wouldoverlap the direction of the electric field, if the liquid crystalalignment direction were rotated in a clockwise direction by a certainacute angle, entirely in a display area surrounded by the pixelelectrode 27 and the common electrode 26 illustrated in FIG. 18.

[0360] If there exists an area in which the liquid crystal alignmentdirection would overlap the direction of the electric field by rotatingthe liquid crystal alignment direction in a counter-clockwise directionby a certain acute angle, the area would generate domain at an end of apixel, in which liquid crystal rotates in a direction opposite to adesired direction, when an electric filed is applied across the pixelelectrode 27 and the common electrode 26. If there exists such a domainas mentioned above, and disclination occurs for a long time at aboundary between the above-mentioned domain in which liquid crystalmolecules rotate in a desired direction and a domain in which liquidcrystal molecules rotate in a direction opposite to a desired direction,display quality would be lowered, and a condition identical with theinitial condition could not be frequently obtained, resulting inreduction in reliability of the liquid crystal display device.

[0361] The above-mentioned reverse rotation of liquid crystal moleculescould be prevented by designing the pixel auxiliary electrode 35 and thecommon electrode lines 26 a and 26 b to have oblique edges, asillustrated in FIG. 18. Herein, in the specification, a structuretwisting liquid crystal molecules only in a single direction bydesigning the pixel auxiliary electrode 35 and the common electrodelines 26 a and 26 b to have oblique edges is called a reverse-rotationpreventing structure.

[0362] Hereinbelow is explained a layer arrangement in areverse-rotation preventing structure 36 in the liquid crystal displaydevice 10.

[0363] In FIG. 19A, the first metal layer is illustrated as obliquelyextending lines with a narrow space, and the second metal layer isillustrated as obliquely extending lines with a wide space. The scanningline 28 and the common electrode lines 26 a and 26 b are comprised ofthe first metal layer, and the data lines 24 and the pixel auxiliaryelectrode 35 is comprised of the second metal layer.

[0364]FIG. 19B illustrates layers composed of ITO. The common electrode26 and the pixel electrode 27 are composed of ITO. The reverse-rotationpreventing structure 36 illustrated in FIG. 18 can be fabricated byoverlaying the layers illustrated in FIG. 19B on the layers illustratedin FIG. 19A with an interlayer insulating film being sandwichedtherebetween.

[0365] By preventing reverse-rotation of molecular axes of liquidcrystal molecules, the liquid crystal display device 10 could haveimproved display quality and reliability. For instance, an electronicdevice such as a personal computer to which the liquid crystal displaydevice 10 is applied can prevent deterioration in display quality byvirtue of the reverse-rotation preventing structure 36.

[0366] For instance, Japanese Patent No. 2973934 (Japanese UnexaminedPatent Publication No. 10-26767) has suggested an example of areverse-rotation preventing structure.

[0367] As illustrated in FIG. 20, the liquid crystal display device 10may be designed to include a passivation film 37 formed on the secondinterlayer insulating film 25, covering the common electrode 26 and thepixel electrode 27 therewith. The alignment film 31 is formed on thepassivation film 37.

[0368] As illustrated in FIG. 21, if an intensive electric field isapplied for a long time across the common electrode 26 and the pixelelectrode 27, misalignment of liquid crystal might occur at edges of thecommon electrode 26 and the pixel electrode 27 which edges face eachother, resulting in display defects.

[0369] The passivation film 37 illustrated in FIG. 20 would weaken theintensive electric field generated at the edges of the common electrode26 and the pixel electrode 27, and thereby prevent misalignment ofliquid crystal molecules and thus display defects.

[0370] A contact hole 39 in the liquid crystal display device 10 (seeFIG. 22) has a square cross-section having 6 μm-long sides. However, alength of the side is not to be limited to 6 μm, but may be longer than6 μm.

[0371] In addition, the contact hole 39 may be designed to have arectangular cross-section, in which case, the contact hole 39necessarily has a shorter side equal to or longer than 6 μm.

[0372] In accordance with the experiments conducted by the inventors,proper electrical connection between upper and lower layers through thecontact hole 39 could not be ensured, if the contact hole 39 had a sideor a shorter side smaller than 6 μm.

[0373] As illustrated in FIG. 22, the contact hole 39 may be coveredwith a metal film 29. The contact hole 39 may be designed to have atapered inner wall, in which case, the contact hole 39 has a size of 6μm×6 μm at its top. The contact hole 39 reaches the common electrodelines 26 a and 26 b. The contact hole illustrated in FIG. 22 and thecontact holes 39 a and 39 b illustrated in FIG. 8 are covered at theirinner walls with the metal film 29, and the metal film 29 is coveredwith an ITO film 46 electrically connected to the common electrode 26(see FIG. 8).

[0374] By covering the contact hole 39 at its inner wall with the metalfilm 29, it would be possible to reduce a resistance between the commonelectrode 26 formed as a transparent electrode and the common electrodeline 26 a or 26 b, and enhance evenness in displaying images.

[0375] The second interlayer insulating film 25 in the liquid crystaldisplay device 10 has a thickness in the range of 1 μm to 2 μm bothinclusive, for instance.

[0376] The second interlayer insulating film 25 in the first embodimentis designed to be comprised of the first film 25 a and the second film25 b, as mentioned earlier. As an alternative, as illustrated in FIG. 9,the second interlayer insulating film 25 may be designed to be comprisedof a single layer composed of inorganic or organic material. The secondinterlayer insulating film 25 illustrated in FIG. 9 is comprised only ofa first film composed of inorganic material. As an alternative, asillustrated in FIG. 8, the second interlayer insulating film 25 may becomprised of a first film composed of inorganic material and a secondfilm covering the first film therewith and composed of organic material.

[0377] Since an organic film has a smaller dielectric constant than thatof an inorganic film, the above-mentioned multi-layered structureincluding the first and second films would lower a dielectric constantof the interlayer insulating film in comparison with an interlayerinsulating film comprised singly of an inorganic film.

[0378] If an interlayer insulating film is comprised singly of anorganic film, an interface between a semiconductor layer in TFT and anorganic film covering the semiconductor layer therewith would beunstable, in which case, if TFT operates at a high temperature, acurrent leaking out of TFT would increase, resulting in displayunevenness. By designing the first film which makes contact with asemiconductor layer of TFT, to be comprised of an inorganic film such asa silicon nitride film, and forming an organic layer on the first film,it would be possible to an interface between the inorganic film and thesemiconductor layer stable, ensuring that the above-mentioned problemcan be solved.

[0379] Examples of the inorganic and organic films are shown in Table 1.TABLE 1 Die- Thick- lectric Film Film ness Con- Formation Pattern- [μm]stant Process ing Inorganic SiNx (Silicon 1-3 6.4 Plasma CVD P1 Filmnitride SiNx/SiOx 1/0.5 6.4/4.0 Plasma P1 (Silicon oxide) CVD/sputtering Inorganic 1-2 4.5 Spin coating P1 polysilazane & baking SiNx/0.15/1-2 6.4/4.5 Plasma P1 Inorganic CVD/spin polysilazane coating &baking Inorganic/ SiNx/Photo- 0.15/1-2 6.4/3.3 Plasma P2 Organicsensitive CVD/spin Films acrylic resin coating SiNx/Photo- 0.15/1-26.4/− Plasma P3 sensitive CVD/spin polyimide coating resin Organic BCB1-2 4.5 Spin coating P4 Film (Benzocyclo- & baking butene) Organic 1-23.8 Spin coating P4 polysilazane & baking Siloxane 1-2 — Spin coating P4& baking

[0380] As shown in Table 1, when the second interlayer insulating film25 is comprised singly of an inorganic film, the inorganic film may beselected from a silicon nitride (SiNx) film, an inorganic polysilazanefilm, a multi-layered structure of a silicon nitride film and a siliconoxide film, and a multi-layered structure of a silicon nitride film andan inorganic polysilazane film.

[0381] When the second interlayer insulating film 25 is comprised singlyof an organic film, the organic film may be selected from abenzocyclobutene (BCB) film, an organic polysilazane film or a siloxanefilm.

[0382] When the second interlayer insulating film 25 is designed to havea multi-layered structure of first and second films, the first film maybe comprised of a silicon nitride film, and the second film may beselected from a photosensitive acrylic resin film or a photosensitivepolyimide resin film.

[0383] Though an inorganic film in the multi-layered structure isindicated as having a thickness of 0.15 μm in Table 1, a thickness of aninorganic film in the multi-layered structure is not to be limited to0.15 μm. An inorganic film in the multi-layered structure may bedesigned to have a thickness in the range of about 0.1 μm to about 1.0μm both inclusive.

[0384] Even if the second film comprised of an organic film had apin-hole between the data line 24 and the common electrode 26 comprisedof a transparent electrode overlapping the data lie 24, the inorganicfilm as the first film could have a sufficient high breakdown voltage bydesigning the inorganic film to have a thickness equal to or greaterthan 0.25 μm, and hence, would prevent the data line 24 and the commonelectrode 26 overlapping the data line 24 from short-circuiting eachother while a panel is being fabricated or images are being displayed,due to dielectric breakage of the interlayer insulating film, andfurther significantly reduce defects of the data line 24 which defectsare caused by the above-mentioned short-circuiting between the data line24 and the common electrode 26.

[0385] It should be noted that thicknesses of the films shown in Table 1are indicated merely as examples, and are not to be limited to specificthicknesses.

[0386] In the liquid crystal display device 10 in accordance with thefirst embodiment, the common electrode 26 to be formed on the secondinterlayer insulating film 25 may be designed to overlap the scanningline 28 and a space formed between the scanning line 28 and the commonelectrode lines 26 a and 26 b, as illustrated in FIG. 23. The commonelectrode 26 having such structure could shield an electric fieldleaking out of the scanning line 28, ensuring an increase in aneffective display area which is controllable by an electric fieldapplied across the pixel electrode 27 and the common electrode 26, andenhancement in an aperture ratio of the liquid crystal display device10.

[0387] Similarly, the common electrode 26 may be designed to overlap achannel region of TFT 30. The common electrode 26 having such structurecould prevent an external electric field intruding TFT 30, ensuringenhancement in both stability of TFT characteristics and reliability todisplayed images.

[0388] As illustrated in FIG. 24, the common electrode line 26 a may beformed in the vicinity of a lower edge in each of pixels, when viewedthrough a plan view of a pixel. That is, the common electrode line 26 amay be positioned immediately above the scanning line 28.

[0389] Since the common electrode 26 is composed of transparentmaterial, a transparent area would be increased by an area occupied bythe common electrode 26, ensuring enhancement in an aperture ratio ofthe liquid crystal display device 10.

[0390] As an alternative, as illustrated in FIG. 25, the commonelectrode line 26 a may be formed in the vicinity of a lower edge ineach of pixels, and the common electrode line 26 b may be formed in thevicinity of an upper edge in each of pixels, when viewed through a planview of a pixel. By forming the common electrode lines 26 a and 26 b inthe vicinity of lower and upper edges of each of pixels, respectively,it would be possible to increase a storage capacitance in comparisonwith one of the common electrode lines 26 a and 26 b being formed in thevicinity of a lower or upper edge of each of pixels.

[0391] In a liquid crystal display device in which TFT 30 is positionedin a lower half in each of pixels when viewed through a plan view of apixel, such as the liquid crystal display device 10 in accordance withthe first embodiment, the pixel electrode 27 and a drain layer definingthe drain electrode 30 a may be electrically connected to each otherthrough a contact hole 39 b in the vicinity of a lower edge of each ofpixels, and the common electrode 26 and the common electrode line 26 bmay be electrically connected to each other through a contact hole 39 ain the vicinity of an upper edge of each of pixels, when viewed througha plan view of a pixel, for instance, as illustrated in FIG. 26.

[0392] In a liquid crystal display device in which TFT 30 is positionedin an upper half in each of pixels when viewed through a plan view of apixel, contrary to the liquid crystal display device 10, the pixelelectrode 27 and a drain layer defining the drain electrode 30 a may beelectrically connected to each other through the contact hole 39 b inthe vicinity of an upper edge of each of pixels, and the commonelectrode 26 and the common electrode line 26 b may be electricallyconnected to each other through the contact hole 39 a in the vicinity ofa lower edge of each of pixels, when viewed through a plan view of apixel, for instance, as illustrated in FIG. 27.

[0393] It would be possible to reduce a total resistance of the commonelectrode 26 by electrically connecting the common electrode 26 to thecommon electrode line 26 a or 26 b through the contact hole 39 a or 39 bin each of pixels, as mentioned above.

[0394] As a method of fabricating the liquid crystal display device 10in accordance with the first embodiment, first to third examples areexplained hereinbelow.

[0395] In the first example of the method of fabricating the liquidcrystal display device 10, the second interlayer insulating film 25 isdesigned to have a multi-layered structure including an inorganic filmand an organic film, as illustrated in FIGS. 28A to 28K. In the secondexample of the method of fabricating the liquid crystal display device10, the second interlayer insulating film 25 is designed to be comprisedsingly of an organic film, as illustrated in FIGS. 29A to 29I. In thethird example of the method of fabricating the liquid crystal displaydevice 10, the second interlayer insulating film 25 is designed to becomprised singly of an inorganic film, as illustrated in FIGS. 30A to30I.

[0396] In FIGS. 28A to 28K, 29A to 29I and 30A to 30I, a region(hereinafter, referred to as “TFT region”) in which TFT is to befabricated, a region (hereinafter, referred to as “pixel region”) inwhich a pixel is to be fabricated, and a region (hereinafter, referredto as “contact hole region”) in which a contact hole used for the commonelectrode 26 is formed are all illustrated in a drawing. The TFT region,the pixel region and the contact hole region are illustrated ascross-sectional views taken along the lines A-A, B-B and C-C in FIG. 10,respectively.

[0397] (First Example)

[0398]FIGS. 28A to 28K are cross-sectional views of the liquid crystaldisplay device 10, illustrating respective steps of the first example ofthe method of fabricating the liquid crystal display device 10 includingthe second interlayer insulating film 25 having a multi-layeredstructure of an inorganic film and an organic film.

[0399] First, as illustrated in FIG. 28A, a chromium layer as the firstmetal layer is formed on a glass substrate as the electricallyinsulating transparent substrate 22, and then, is patterned byphotolithography and dry etching into the gate electrode 30 c and thecommon electrode lines 26 a and 26 b. Though only the common electrodeline 26 b is illustrated in FIGS. 28A to 30I, the common electrode line26 a together with the common electrode line 26 b will be explainedhereinbelow, because the common electrode line 26 a is formed togetherwith the common electrode line 26 b.

[0400] Then, as illustrated in FIG. 28B, the first interlayer insulatingfilm 23 is formed all over the transparent substrate 22, covering thegate electrode 30 c and the common electrode lines 26 a and 26 btherewith. The first interlayer insulating film 23 has a multi-layeredstructure of a silicon dioxide (SiO₂) film and a silicon nitride (SiNx)film.

[0401] Then, as illustrated in FIG. 28C, an amorphous silicon filmcomprised of an a-Si film 32 and a n+ a-Si film 33 is formed entirely onthe first interlayer insulating film 23.

[0402] Then, as illustrated in FIG. 28D, the a-Si film 32 and the n+a-Si film 33 are patterned into an island-shaped semiconductor layer byphotolithography and dry etching.

[0403] Then, a chromium layer as the second metal layer is formed allover the substrate 22. Then, the chromium layer is patterned into thedrain electrode 30 a, the source electrode 30 b, the data line 24, andthe pixel auxiliary electrode 35 by photolithography and dry etching, asillustrated in FIG. 28E.

[0404] Then, as illustrated in FIG. 28F, the n+ a-Si film 33 and thea-Si film 32 are etched throughout an entire thickness of the +a-Si film33 and until a certain depth of the a-Si film 32 at an opening formedbetween the drain electrode 30 a and the source electrode 30 b with thedrain electrode 30 a and the source electrode 30 b being used as a mask,to thereby form a channel of TFT 30.

[0405] Then, as illustrated in FIG. 28G, the first film 25 a comprisedof a silicon nitride film as an inorganic film and defining the secondinterlayer insulating film 25 together with the second film 25 b isformed all over the substrate 22.

[0406] Then, as illustrated in FIG. 28H, the second film 25 b comprisedof a photosensitive acrylic resin film as an organic film is formed onthe first film 25 a.

[0407] Then, as illustrated in FIG. 28I, the second film 25 b of thesecond interlayer insulating film 25 is exposed to a light, developed,and then, baked, to thereby form the contact hole 39 b reaching thesilicon nitride film of the first interlayer insulating film 23 abovethe source electrode 30 b and the contact hole 39 a reaching the siliconnitride film of the first interlayer insulating film 23 above the commonelectrode line 26 b.

[0408] Then, as illustrated in FIG. 28J, the exposed first film 25 a isetched through the contact hole 39 b, and the exposed first film 25 aand the first interlayer insulating film 23 having a multi-layeredstructure of a silicon dioxide film and a silicon nitride film areetched through the contact hole 39 a to thereby allow the contact holes39 a and 39 b to reach the source electrode 30 b and the commonelectrode line 26 a or 26 b, respectively.

[0409] Then, the ITO film 46 is formed all over the resultant such thatthe contact holes 39 a and 39 b are covered at inner walls thereof withthe ITO film 46. Then, as illustrated in FIG. 28K, the ITO film 46 isetched by photolithography and etching to thereby form the commonelectrode 26 and the pixel electrode 27 both composed of the ITO film 46in each of regions where a unit pixel is to be formed.

[0410] (Second Example)

[0411]FIGS. 29A to 29I are cross-sectional views of the liquid crystaldisplay device 10, illustrating respective steps of the second exampleof the method of fabricating the liquid crystal display device 10including the second interlayer insulating film 25 comprised singly ofan organic film.

[0412] First, as illustrated in FIG. 29A, a chromium layer as the firstmetal layer is formed on a glass substrate as the electricallyinsulating transparent substrate 22, and then, is patterned byphotolithography and dry etching into the gate electrode 30 c and thecommon electrode lines 26 a and 26 b.

[0413] Then, as illustrated in FIG. 29B, the first interlayer insulatingfilm 23 is formed all over the transparent substrate 22, covering thegate electrode 30 c and the common electrode lines 26 a and 26 btherewith. The first interlayer insulating film 23 has a multi-layeredstructure of a silicon dioxide (SiO) film and a silicon nitride (SiNx)film.

[0414] Then, as illustrated in FIG. 29C, an amorphous silicon filmcomprised of an a-Si film 32 and a n+ a-Si film 33 is formed entirely onthe first interlayer insulating film 23.

[0415] Then, as illustrated in FIG. 29D, the a-Si film 32 and the n+a-Si film 33 are patterned into an island-shaped semiconductor layer byphotolithography and dry etching.

[0416] Then, a chromium layer as the second metal layer is formed allover the resultant. Then, the chromium layer is patterned into the drainelectrode 30 a, the source electrode 30 b, the data line 24, and thepixel auxiliary electrode 35 by photolithography and dry etching, asillustrated in FIG. 29E.

[0417] Then, as illustrated in FIG. 29F, the n+ a-Si film 33 and thea-Si film 32 are etched throughout an entire thickness of the +a-Si film33 and until a certain depth of the a-Si film 32 at an opening formedbetween the drain electrode 30 a and the source electrode 30 b with thedrain electrode 30 a and the source electrode 30 b being used as a mask,to thereby form a channel of TFT 30.

[0418] Then, as illustrated in FIG. 29G, the second interlayerinsulating film 25 comprised singly of a photosensitive acrylic resinfilm as an organic film is formed entirely over the resultant.

[0419] Then, as illustrated in FIG. 29H, the second interlayerinsulating film 25 comprised singly of a photo-sensitive acrylic resinfilm is exposed to a light and developed to thereby form the contacthole 39 b reaching the source electrode 30 b and the contact hole 39 areaching the first interlayer insulating film 23 above the commonelectrode line 26 a or 26 b.

[0420] Then, the exposed first interlayer insulating film 23 is etchedthrough the contact hole 39 a to thereby extend the contact hole 39 a tothe common electrode line 26 a or 26 b.

[0421] Then, as illustrated in FIG. 29I, the ITO film 46 is formed allover the resultant such that the contact holes 39 a and 39 b are coveredat inner walls thereof with the ITO film 46. Then, the ITO film 46 isetched by photolithography and etching to thereby form the commonelectrode 26 and the pixel electrode 27 both composed of the ITO film46.

[0422] (Third Example)

[0423]FIGS. 30A to 30I are cross-sectional views of the liquid crystaldisplay device 10, illustrating respective steps of the third example ofthe method of fabricating the liquid crystal display device 10 includingthe second interlayer insulating film 25 comprised singly of aninorganic film.

[0424] First, as illustrated in FIG. 30A, a chromium layer as the firstmetal layer is formed on a glass substrate as the electricallyinsulating transparent substrate 22, and then, is patterned byphotolithography and dry etching into the gate electrode 30 c and thecommon electrode lines 26 a and 26 b.

[0425] Then, as illustrated in FIG. 30B, the first interlayer insulatingfilm 23 is formed all over the transparent substrate 22, covering thegate electrode 30 c and the common electrode lines 26 a and 26 btherewith. The first interlayer insulating film 23 has a multi-layeredstructure of a silicon dioxide (SiO₂) film and a silicon nitride (SiNx)film.

[0426] Then, as illustrated in FIG. 30C, an amorphous silicon filmcomprised of an a-Si film 32 and a n+ a-Si film 33 is formed entirely onthe first interlayer insulating film 23.

[0427] Then, as illustrated in FIG. 30D, the a-Si film 32 and the n+a-Si film 33 are patterned into an island-shaped semiconductor layer byphotolithography and dry etching.

[0428] Then, a chromium layer as the second metal layer is formed allover the resultant. Then, the chromium layer is patterned into the drainelectrode 30 a, the source electrode 30 b, the data line 24, and thepixel auxiliary electrode 35 by photolithography and dry etching, asillustrated in FIG. 30E.

[0429] Then, as illustrated in FIG. 30F, the n+ a-Si film 33 and thea-Si film 32 are etched throughout an entire thickness of the +a-Si film33 and until a certain depth of the a-Si film 32 at an opening formedbetween the drain electrode 30 a and the source electrode 30 b with thedrain electrode 30 a and the source electrode 30 b being used as a mask,to thereby form a channel of TFT 30.

[0430] Then, as illustrated in FIG. 30G, the second interlayerinsulating film 25 comprised singly of a silicon nitride film as aninorganic film is formed entirely over the resultant.

[0431] Then, as illustrated in FIG. 30H, the second interlayerinsulating film 25 comprised singly of a silicon nitride film is etchedby photolithography to thereby form the contact holes 39 a and 39 b.Then, the first interlayer insulating film 23 is etched through thecontact hole 39 a. Thus, the contact hole 39 b reaches the sourceelectrode 30 b, and the contact hole 39 a reaches the common electrodelines 26 a and 26 b.

[0432] Then, as illustrated in FIG. 30I, the ITO film 46 is formed allover the resultant such that the contact holes 39 a and 39 b are coveredat inner walls thereof with the ITO film 46. Then, the ITO film 46 isetched by photolithography and etching to thereby form the commonelectrode 26 and the pixel electrode 27 both composed of the ITO film46.

[0433] By carrying out the above-mentioned first, second or thirdexamples of the method of fabricating the liquid crystal display device10, a scanning line terminal, a data line terminal and a commonelectrode line terminal are formed around the TFT region, the pixelregion and the contact hole region. Hereinbelow are explained the stepsof forming those regions.

[0434]FIG. 31 illustrates an arrangement of the scanning line 28, thedata line 24, and the common electrode lines 26 a and 26 b in the liquidcrystal display device 10, and FIG. 32 illustrates a positional relationamong a scanning line terminal 41 c, a data line terminal 41 d and acommon electrode line terminal 41 d in the liquid crystal display device10. FIG. 32 illustrates an arrangement in which the common electrodelines 26 a and 26 b are formed in the vicinity of upper and lower edgesin each of pixels, as illustrated in FIG. 25.

[0435] With reference to FIG. 31, the scanning line 28 horizontallyextends in the vicinity of a lower edge in each of pixels, the commonelectrode line 26 a extends immediately above and in parallel with thescanning line 28, and the common electrode line 26 b horizontallyextends in the vicinity of an upper edge in each of pixels. The scanningline 28 and the common electrode lines 26 a and 26 b are comprised ofthe first metal layer. In FIG. 31, the data line 24 extendsperpendicularly to the scanning line 28 and the common electrode lines26 a and 26 b in the vicinity of boundaries between pixels. The dataline 24 is comprised of the second metal layer. The common electrodelines 26 a and 26 b are electrically connected to each other outside apixel area where a plurality of pixels are arranged in a matrix.

[0436] With reference to FIG. 32, the common electrode line terminal 41e and the scanning line terminal 41 c are located outside and at theleft of the pixel area, and the data line terminal 41 d is locatedoutside and above the pixel area. The common electrode line terminal 41e, the scanning line terminal 41 c and the data line terminal 41 d areformed with contact holes 39 e, 39 c and 39 d, respectively. The contactholes 39 e, 39 c and 39 d are covered with ITO covers 38 e, 38 c and 38d, respectively.

[0437] Hereinbelow are explained three examples of a method offabricating the liquid crystal display device 10. In the first example,the second interlayer insulating film 25 is designed to have amulti-layered structure including an inorganic film and an organic film,as illustrated in FIGS. 33A to 33J. In the second example, the secondinterlayer insulating film 25 is designed to be comprised singly of anorganic film, as illustrated in FIGS. 34A to 34I. In the third example,the second interlayer insulating film 25 is designed to be comprisedsingly of an inorganic film, as illustrated in FIGS. 35A to 35H.

[0438] In FIGS. 33A to 33J, 34A to 34I and 35A to 35H, the commonelectrode line terminal 41 e, the scanning line terminal 41 c and thedata line terminal 41 d are all illustrated in a single drawing. Thecommon electrode line terminal 41 e and the scanning line terminal 41 care illustrated as a cross-sectional view taken along the line D-D inFIG. 32, and the data line terminal 41 d is illustrated as across-sectional view taken along the line E-E in FIG. 32.

[0439] (First Example)

[0440]FIGS. 33A to 33J are cross-sectional views of the liquid crystaldisplay device 10, illustrating respective steps of the first example ofthe method of fabricating the liquid crystal display device 10 includingthe second interlayer insulating film 25 having a multi-layeredstructure of an inorganic film and an organic film.

[0441] First, as illustrated in FIG. 33A, a chromium layer as the firstmetal layer is formed on a glass substrate as the electricallyinsulating transparent substrate 22, and then, is patterned byphotolithography and dry etching into the common electrode lines 26 aand 26 b and the scanning line 28 in both the common electrode lineterminal 41 e and the scanning line terminal 41 c.

[0442] Though only the common electrode line 26 b is illustrated inFIGS. 33A to 35H, the common electrode line 26 a together with thecommon electrode line 26 b will be explained hereinbelow, because thecommon electrode line 26 a is formed together with the common electrodeline 26 b.

[0443] Then, as illustrated in FIG. 33B, the first interlayer insulatingfilm 23 is formed all over the transparent substrate 22, covering thecommon electrode lines 26 a and 26 b and the scanning line 28 therewith.The first interlayer insulating film 23 has a multi-layered structure ofa silicon dioxide (SiO₂) film and a silicon nitride (SiNx) film.

[0444] Then, as illustrated in FIG. 33C, an amorphous silicon film(a-Si) film 32 is formed entirely on the first interlayer insulatingfilm 23.

[0445] Then, as illustrated in FIG. 33D, a n+ a-Si film 33 is formedentirely on the a-Si film 32.

[0446] Then, the a-Si film 32 and the n+ a-Si film 33 are patterned intoan island (for instance, see FIG. 28D). Then, a chromium layer as thesecond metal layer is formed on the transparent substrate 22, coveringthe island-shaped a-Si film 32 and the n+ a-Si film 33 therewith.

[0447] Then, as illustrated in FIG. 33E, the chromium layer is patternedby photolithography and dry etching into the data line 24 in the dataline terminal 41 d.

[0448] Then, as illustrated in FIG. 33F, the first film 25 a comprisedof a silicon nitride film as an inorganic film and defining the secondinterlayer insulating film 25 together with the second film 25 b isformed all over the first interlayer insulating film 23, covering thedata line 24 therewith.

[0449] Then, as illustrated in FIG. 33G, the second film 25 b comprisedof a photosensitive acrylic resin film as an organic film is formed onthe first film 25 a.

[0450] Then, as illustrated in FIG. 33H, the second film 25 b of thesecond interlayer insulating film 25 is etched to thereby form contactholes 39 e and 39 c both reaching the first film 25 a above the commonelectrode lines 26 a and 26 b and the scanning line 28, in both thecommon electrode line terminal 41 e and the scanning line terminal 41 c,and further form a contact hole 39 d reaching the first film 25 a abovethe data line 24, in the data line terminal 41 d.

[0451] Then, as illustrated in FIG. 33I, the first film 25 a exposedthrough the contact holes 39 e, 39 c and 39 d and the first interlayerinsulating film 23 are etched through the contact holes 39 e, 39 c and39 d to thereby allow the contact holes 39 e, 39 c and 39 d to reach thecommon electrode line 26 b, the scanning line 28 and the data line 24,respectively.

[0452] Then, the ITO film 46 is formed all over the resultant such thatthe contact holes 39 e, 39 c and 39 d are covered at inner walls thereofwith the ITO film 46. Then, as illustrated in FIG. 33J, the ITO film 46is patterned by photolithography and etching such that the ITO film 46makes electrical contact with the common electrode line 26 b, thescanning line 28 and the data line 24 at bottoms of the contact holes 39e, 39 c and 39 d, respectively.

[0453] (Second Example)

[0454]FIGS. 34A to 34I are cross-sectional views of the liquid crystaldisplay device 10, illustrating respective steps of the second exampleof the method of fabricating the liquid crystal display device 10including the second interlayer insulating film 25 comprised singly ofan organic film.

[0455] First, as illustrated in FIG. 34A, a chromium layer as the firstmetal layer is formed on a glass substrate as the electricallyinsulating transparent substrate 22, and then, is patterned byphotolithography and dry etching into the common electrode lines 26 aand 26 b and the scanning line 28 in both the common electrode lineterminal 41 e and the scanning line terminal 41 c.

[0456] Then, as illustrated in FIG. 34B, the first interlayer insulatingfilm 23 is formed all over the transparent substrate 22, covering thecommon electrode lines 26 a and 26 b and the scanning line 28 therewith.The first interlayer insulating film 23 has a multi-layered structure ofa silicon dioxide (SiO₂) film and a silicon nitride (SiNx) film.

[0457] Then, as illustrated in FIG. 34C, an amorphous silicon film(a-Si) film 32 is formed entirely on the first interlayer insulatingfilm 23.

[0458] Then, as illustrated in FIG. 34D, a n+ a-Si film 33 is formedentirely on the a-Si film 32.

[0459] Then, the a-Si film 32 and the n+ a-Si film 33 are patterned intoan island (for instance, see FIG. 28D). Then, a chromium layer as thesecond metal layer is formed on the transparent substrate 22, coveringthe island-shaped a-Si film 32 and the n+ a-Si film 33 therewith.

[0460] Then, as illustrated in FIG. 34E, the chromium layer is patternedby photolithography and dry etching into the data line 24 in the dataline terminal 41 d.

[0461] Then, as illustrated in FIG. 34F, the second interlayerinsulating film 25 comprised of a photo-sensitive acrylic resin film asan organic film is formed all over the first interlayer insulating film23, covering the data line 24 therewith.

[0462] Then, as illustrated in FIG. 34G, the second interlayerinsulating film 25 is etched to thereby form contact holes 39 e and 39 cboth reaching the first interlayer insulating film 23 above the commonelectrode lines 26 a and 26 b and the scanning line 28, in both thecommon electrode line terminal 41 e and the scanning line terminal 41 c,and further form a contact hole 39 d reaching the data line 24, in thedata line terminal 41 d.

[0463] Then, as illustrated in FIG. 34H, the first interlayer insulatingfilm 23 exposed through the contact holes 39 e, and 39 c is etchedthrough the contact holes 39 e and 39 c to thereby allow the contacthole 39 e to reach the common electrode lines 26 a and 26 b, and furtherallow the contact hole 39 c to reach the scanning line 28.

[0464] Then, the ITO film 46 is formed all over the resultant such thatthe contact holes 39 e, 39 c and 39 d are covered at inner walls thereofwith the ITO film 46. Then, as illustrated in FIG. 34I, the ITO film 46is patterned by photolithography and etching such that the ITO film 46makes electrical contact with the common electrode lines 26 a and 26 b,the scanning line 28 and the data line 24 at bottoms of the contactholes 39 e, 39 c and 39 d, respectively.

[0465] (Third Example)

[0466]FIGS. 35A to 35H are cross-sectional views of the liquid crystaldisplay device 10, illustrating respective steps of the third example ofthe method of fabricating the liquid crystal display device 10 includingthe second interlayer insulating film 25 comprised singly of aninorganic film.

[0467] First, as illustrated in FIG. 35A, a chromium layer as the firstmetal layer is formed on a glass substrate as the electricallyinsulating transparent substrate 22, and then, is patterned byphotolithography and dry etching into the common electrode lines 26 aand 26 b and the scanning line 28 in both the common electrode lineterminal 41 e and the scanning line terminal 41 c.

[0468] Then, as illustrated in FIG. 35B, the first interlayer insulatingfilm 23 is formed all over the transparent substrate 22, covering thecommon electrode lines 26 a and 26 b and the scanning line 28 therewith.The first interlayer insulating film 23 has a multi-layered structure ofa silicon dioxide (SiO₂) film and a silicon nitride (SiNx) film.

[0469] Then, as illustrated in FIG. 35C, an amorphous silicon film(a-Si) film 32 is formed entirely on the first interlayer insulatingfilm 23.

[0470] Then, as illustrated in FIG. 35D, a n+ a-Si film 33 is formedentirely on the a-Si film 32.

[0471] Then, the a-Si film 32 and the n+ a-Si film 33 are patterned intoan island (for instance, see FIG. 28D). Then, a chromium layer as thesecond metal layer is formed on the transparent substrate 22, coveringthe island-shaped a-Si film 32 and the n+ a-Si film 33 therewith.

[0472] Then, as illustrated in FIG. 35E, the chromium layer is patternedby photolithography and dry etching into the data line 24 in the dataline terminal 41 d.

[0473] Then, as illustrated in FIG. 35F, the second interlayerinsulating film 25 comprised of a silicon nitride film as an inorganicfilm is formed all over the first interlayer insulating film 23,covering the data line 24 therewith.

[0474] Then, as illustrated in FIG. 35G, the second interlayerinsulating film 25 is etched to thereby form contact holes 39 e and 39 cboth reaching the first interlayer insulating film 23 above the commonelectrode lines 26 a and 26 b and the scanning line 28, in both thecommon electrode line terminal 41 e and the scanning line terminal 41 c,and further form a contact hole 39 d reaching the data line 24, in thedata line terminal 41 d.

[0475] Then, the first interlayer insulating film 23 exposed through thecontact holes 39 e, and 39 c is etched through the contact holes 39 eand 39 c to thereby allow the contact hole 39 e to reach the commonelectrode lines 26 a and 26 b, and further allow the contact hole 39 cto reach the scanning line 28.

[0476] Then, as illustrated in FIG. 35H, the ITO film 46 is formed allover the resultant such that the contact holes 39 e, 39 c and 39 d arecovered at inner walls thereof with the ITO film 46. Then, the ITO film46 is patterned by photolithography and etching such that the ITO film46 makes electrical contact with the common electrode lines 26 a and 26b, the scanning line 28 and the data line 24 at bottoms of the contactholes 39 e, 39 c and 39 d, respectively.

[0477] [Second Embodiment]

[0478]FIGS. 36 and 37 illustrate an in-plane switching mode liquidcrystal display device 80 in accordance with the second embodiment ofthe present invention. FIG. 36 is a plan view of the liquid crystaldisplay device 80, and FIG. 37 is a cross-sectional view taken along theline XXX VII-XXX VII in FIG. 36.

[0479] The in-plane switching mode liquid crystal display device 80 inaccordance with the second embodiment is structurally different from theliquid crystal display device 10 in accordance with the first embodiment10 illustrated in FIGS. 4 and 5 in that the pixel electrode 27 is formednot on the second film 25 b of the second interlayer insulating film 25,but on the first interlayer insulating film 23, and that, the pixelelectrode 27 is comprised of the second metal layer.

[0480] Since the pixel electrode 27 is comprised of the second metallayer 27, the liquid crystal display device 80 has a smaller apertureratio than that of the liquid crystal display device 10. However, sincethe pixel electrode 27 is comprised of a layer different from a layer ofwhich the common electrode 26 is formed, in the second embodiment, thepixel electrode 27 and the common electrode 26 would not beshort-circuited each other, ensuring enhancement in a fabrication yield.

[0481] [Third Embodiment]

[0482]FIGS. 38 and 39 illustrate an in-plane switching mode liquidcrystal display device 85 in accordance with the third embodiment of thepresent invention. FIG. 38 is a plan view of the liquid crystal displaydevice 85, and FIG. 39 is a cross-sectional view taken along the lineXXX IX-XXX IX in FIG. 38.

[0483] As illustrated in FIG. 39, in the in-plane switching mode liquidcrystal display device 85 in accordance with the third embodiment, thefirst film 25 a constituting the second interlayer insulating film 25together with the second film 25 b is formed entirely over a pixel area,whereas the second film 25 b is formed only below the common electrode26.

[0484] In a display area of a pixel, the common electrode 26 iscomprised of the first metal layer of which the gate electrode isformed, in an area other than an area in which the common electrode 26is composed of transparent metal, overlapping the data line 24.

[0485] In accordance with the third embodiment, it is no longernecessary to form the second film 25 b in a large area more thannecessary, and thereby, it would be possible to prevent an increase in aparasitic capacity between the common electrode 26 and the data line 24.

[0486] The pixel electrode 27 may be formed on the first interlayerinsulating film 23 together with the data line 24.

[0487] Since the common electrode 26 is comprised of the first metallayer in an area other than an area in which the common electrode 26 iscomposed of a transparent metal film formed on the second film 25 b, thein-plane switching mode liquid crystal display device 85 in accordancewith the third embodiment has a smaller aperture ratio than that of theliquid crystal display device 10 in accordance with the firstembodiment. However, since the common electrode 26 is comprised of alayer different from a layer of which the pixel electrode 27 is formed,the common electrode 26 and the pixel electrode 27 would not beshort-circuited each other, ensuring enhancement in a fabrication yield.

[0488] [Fourth Embodiment]

[0489]FIGS. 40 and 41 illustrate an in-plane switching mode liquidcrystal display device 100 in accordance with the fourth embodiment ofthe present invention. FIG. 40 is a plan view of the liquid crystaldisplay device 100, and FIG. 41 is a cross-sectional view taken alongthe line XXXX I-XXXX I in FIG. 40. In FIG. 64, a TFT region, a pixelregion, and a contact hole region are illustrated all in a singledrawing. The TFT region, the pixel region and the contact hole regionare illustrated as cross-sectional views taken along the lines A-A, XXXXI-XXXX I, and C-C in FIG. 40, respectively.

[0490] As illustrated in FIG. 41, the liquid crystal display device 100is comprised of an active device substrate 111, an opposing substrate112, and a liquid crystal layer 113 sandwiched between the active devicesubstrate 111 and the opposing substrate 112.

[0491] The opposing substrate 112 includes an electrically insulatingtransparent substrate 116, a black matrix layer 117 formed on a firstsurface of the electrically insulating transparent substrate 116 as alight-impermeable film, a color layer 118 formed on the first surface ofthe electrically insulating transparent substrate 116 such that thecolor layer 118 partially overlaps the black matrix layer 117, and atransparent over-coating layer 119 covering the black matrix layer 117and the color layer 118 therewith.

[0492] The color layer 118 is comprised of resin films containing red(R), green (G) and blue (B) pigments.

[0493] The opposing substrate 112 further includes an electricallyconductive transparent layer 115 on a second surface of the electricallyinsulating transparent substrate 116 in order to prevent electriccharges caused by contact of a liquid crystal display panel with othermaterials, from exerting electrical influence on the liquid crystallayer 113.

[0494] The active matrix substrate 11 includes an electricallyinsulating transparent substrate 122, a first metal layer formed on theelectrically insulating transparent substrate 122 and defining ascanning line 128 and a gate electrode 130 c therein, a first interlayerinsulating film 123 formed on the electrically insulating transparentsubstrate 122, an island-shaped amorphous silicon film formed on thefirst interlayer insulating film 123, a second metal layer defining adata line 124, and a source electrode 130 b and a drain electrode 130 aof a thin film transistor (TFT) 130 therein, a first film 25 a formed onthe first interlayer insulating film 123, a second film 125 b formed onthe first film 125 a, and a common electrode 26 and a pixel electrode 27formed as transparent electrodes on the second film 125 b.

[0495] The island-shaped amorphous silicon film has a multi-layeredstructure comprised of an a-Si film 132, and a n+ a-Si film 133 formedon the a-Si film 132.

[0496] The first and second films 125 a and 125 b constitute a secondelectrically insulating film 125.

[0497] The active matrix substrate 111 further includes a pixelauxiliary electrode 135 formed on the first interlayer insulating film123 together with the data lines 124. The data lines 124 and the pixelauxiliary electrode 135 are composed of the second metal layer.

[0498] The active device substrate 111 and the opposing substrate 112include alignment films 131 and 132, respectively, both making contactwith the liquid crystal layer 113. After being rubbed in a directionindicated in FIG. 40, the active device substrate 111 and the opposingsubstrate 112 are coupled with each other.

[0499] Though not illustrated, spacers are sandwiched between the activedevice substrate 111 and the opposing substrate 112 to ensure athickness of the liquid crystal layer 113, and a seal is formed aroundthe liquid crystal layer 113 between the active device substrate 111 andthe opposing substrate 112 for avoiding leakage of liquid crystalmolecules.

[0500] The active device substrate 111 further includes a polarizingplate 121 formed on a lower surface of the electrically insulatingtransparent substrate 122, and similarly, the opposing substrate 112includes a polarizing plate 114 formed on the electrically conductivelayer 115. The polarizing plate 121 of the active device substrate 111has a polarization axis extending perpendicularly to the liquid crystalinitial alignment direction, and the polarizing plate 114 of theopposing substrate 112 has a polarization axis extending in parallel tothe liquid crystal initial alignment direction. The polarization axesextend perpendicularly to each other.

[0501] As illustrated in FIG. 40, the active device substrate 111includes data lines 24 to which data signals are transmitted, a commonelectrode 26 to which a reference voltage is applied, a pixel electrode27 associated with pixels in which images are to be displayed, ascanning line 28 to which a scanning signal is applied, and a thin filmtransistor (TFT) 130.

[0502] The thin film transistor 130 includes a gate electrode 130 c, adrain electrode 130 a, and a source electrode 130 b. The thin filmtransistor 130 is located in the vicinity of an intersection of thescanning line 128 and the data line 124 in association with a pixel.

[0503] The gate electrode 130 c is electrically connected to thescanning line 128, the drain electrode 130 a is electrically connectedto the data line 124, and the source electrode 130 b is electricallyconnected to the pixel electrode 127.

[0504] Both the common electrode 126 and the pixel electrode 127 aredesigned to have a comb-teeth shape, and the comb-teeth in the commonelectrode 126 and the pixel electrode 127 extend in parallel with thedata lines 124. That is, as illustrated in FIG. 42A, the liquid crystaldisplay device 100 is of a type where an opening 111 a of the activedevice substrate 111 extends in a direction in which the data line 124also extends.

[0505] The comb-teeth in the common electrode 126 and the pixelelectrode 127 in the fourth embodiment are designed to be in a zigzagform unlike the comb-teeth of the common electrode 26 and the pixelelectrode 27 in the first embodiment. The comb-teeth of the commonelectrode 126 and the comb-teeth of the pixel electrode 127 are arrangedto be in mesh with each other, and further spaced away from each other.

[0506] In the in-plane switching mode liquid crystal display device 100,an electric field is generated between the common electrode 126 and thepixel electrode 127 in parallel with the electrically insulatingtransparent substrates 116 and 122 in a pixel which is selected by ascanning signal transmitted through the scanning line 128 and into whicha data signal transmitted through the data line 124 is written. The thusgenerated electric field has a direction dependent on a direction inwhich the common electrode 126 and the pixel electrode 127 are bent.

[0507] As illustrated in FIG. 40, an area occupied by a pixel is dividedinto a first pixel sub-area and a second pixel sub-area in dependence ona direction in which the common electrode 126 and the pixel electrode127 are bent, that is, a direction of an electric field applied acrossthe common electrode 126 and the pixel electrode 127. In the first andsecond pixel sub-areas, directors of liquid crystal molecules arerotated in opposite directions in accordance with the applied electricfield in a plane which is parallel with a surface of the active devicesubstrate 111, to thereby display images. That is, the liquid crystaldisplay device 100 in accordance with the fourth embodiment is ofso-called multi-domain type.

[0508] A direction of an electric field applied across the commonelectrode 126 and the pixel electrode 127 varies in dependence on anarea therebetween. To be exact, an area occupied by a pixel can bedivided into a first pixel sub-area in which directors of liquid crystalmolecules rotate in a clockwise direction, and a second pixel sub-areain which directors of liquid crystal molecules rotate in acounter-clockwise direction. A pixel sub-area may be called a domain.

[0509] By designing directors of liquid crystal molecules to rotate inopposite directions to each other in the first and second pixelsub-areas, the first and second pixel sub-areas optically compensate foreach other. Hence, it would be possible to prevent images from beingcolored when viewed obliquely, and further prevent inversion ofgradation which occurs between black-display and rather darkintermediate tone, ensuring enhancement in viewing angle characteristic.

[0510] In the liquid crystal display device 100, both the commonelectrode 126 and the pixel electrode 127 are composed of ITO which isone of transparent materials.

[0511] As illustrated in FIG. 41, the common electrode 126 is formed ona layer other than a layer on which the data line 124 is formed, and inaddition, the common electrode 126 entirely overlaps the data line 124similarly to the first embodiment.

[0512] As illustrated in FIG. 40, the common electrode 126 iselectrically connected to the common electrode line 126 a or 126 bthrough the contact hole 139 a (see FIG. 61), and the pixel electrode127 is electrically connected to the source electrode 130 b through thecontact hole 139 b (see FIG. 61).

[0513] The black matrix layer 117 overlapping the data line 124 isdesigned to have a width smaller than a width f the common electrode126.

[0514] No light-permeable film exists between a portion of the commonelectrode 126 which portion overlaps the data line 124 and the pixelelectrode 127 located closest to the portion.

[0515] Similarly to the first embodiment, the black matrix layer 117formed above the data line 124 overlaps the data line 124 in its entirelength.

[0516] In addition, as illustrated in FIG. 40, the data line 124 in theliquid crystal display device 100 is designed to have a zigzag form.

[0517] That is, the liquid crystal display device 100 in accordance withthe fourth embodiment has the same structure as that of the liquidcrystal display device 10 in accordance with the first embodiment exceptthat the liquid crystal display device 100 is of multi-domain type, andthat the common electrode 126, the pixel electrode 127 and the data line124 are zigzag-shaped.

[0518] The term “zigzag” in the fourth embodiment indicates not only ashape having linear portions all inclined relative to a length-wisedirection Z, as illustrated in FIG. 43A, but also a shape having bothfirst linear portions inclined relative to a length-wise direction Z andsecond linear portions extending in parallel with the length-wisedirection Z where the first and second linear portions are alternatelyconnected to each other, as illustrated in FIG. 43B. In other words, theterm “zigzag” includes all shapes repeating inclination alternately tothe left and right relative to a length-wise direction thereof, butextending in the length-wise direction. It does not matter as to whethera “zigzag” includes a linear portion extending in parallel with alength-wise direction Z thereof. An angle by which the second linearportion inclines relative to the length-wise direction Z thereof is notto be limited to a specific angle, and in addition, it is not alwaysnecessary for angles by which the second linear portions inclinerelative to the length-wise direction Z to be constant.

[0519] The liquid crystal display device 100 in accordance with thefourth embodiment provides the same advantages as those obtained by theliquid crystal display device 10 in accordance with the firstembodiment.

[0520] The zigzag-shaped data line 124 could increase an aperture ratioof the liquid crystal display device 100 in comparison with a liquidcrystal display device having a linear data line. The reason therefor isexplained hereinbelow.

[0521]FIG. 44 is a plan view of a liquid crystal display device 201including a linear data line, a linear common electrode, and a linearpixel electrode, and FIG. 45 is a cross-sectional view taken along theline XXXX V-XXXX V in FIG. 44.

[0522] The electrodes and other parts constituting the liquid crystaldisplay device 201 illustrated in FIG. 44 have dimensions as follows.Dimensions indicated hereinbelow are expressed in a unit of micrometers(μm), unless otherwise indicated.

[0523] Width of the data line 24=10

[0524] Width of the common electrode 26 located immediately above thedata line 24=19

[0525] Width of other common electrodes 26 formed on a layer on whichthe common electrode 26 located immediately above the data line 24 isformed=3.5

[0526] Width of the pixel electrode 27=3.5

[0527] Distance between the common electrode 26 and the pixel electrode27=0.5

[0528] Accordingly, a total area A1 of openings in the liquid crystaldisplay device 201 illustrated in FIG. 44 is calculated as follows.

A 1=(9.5×6)×L=57L

[0529] L indicates a longitudinal length of the openings.

[0530]FIG. 46 is a plan view of a liquid crystal display device 202including a linear data line, a zigzag-shaped common electrode, and azigzag-shaped pixel electrode, and FIG. 47 is a cross-sectional viewtaken along the line XXXX VII-XXXX VII in FIG. 46.

[0531] The electrodes and other parts constituting the liquid crystaldisplay device 202 illustrated in FIG. 46 have dimensions as follows.

[0532] Width of the data line 124=10

[0533] Width of the common electrode 126 located immediately above thedata line 124=26.5

[0534] Width of other common electrodes 126 formed on a layer on whichthe common electrode 126 located immediately above the data line 124 isformed=3.5

[0535] Width of the pixel electrode 127=3.5

[0536] Distance between the common electrode 126 and the pixel electrode127=8.2

[0537] Accordingly, a total area A2 of openings in the liquid crystaldisplay device 202 illustrated in FIG. 46 is calculated as follows.

A 2=(8.2×6)×L=49.2L

[0538]FIG. 48 is a plan view of a liquid crystal display device 203including a zigzag-shaped data line, a zigzag-shaped common electrode,and a zigzag-shaped pixel electrode, that is, a plan view of the liquidcrystal display device 100 in accordance with the first embodiment, andFIG. 49 is a cross-sectional view taken along the line XXXX IX-XXXX IXin FIG. 48.

[0539] The electrodes and other parts constituting the liquid crystaldisplay device 203 illustrated in FIG. 48 have dimensions as follows.

[0540] Width of the data line 124=10

[0541] Width of the common electrode 126 located immediately above thedata line 124=19

[0542] Width of other common electrodes 126 formed on a layer on whichthe common electrode 126 located immediately above the data line 124 isformed=3.5

[0543] Width of the pixel electrode 127=3.5

[0544] Distance between the common electrode 126 and the pixel electrode127=9.5

[0545] Accordingly, a total area A3 of openings in the liquid crystaldisplay device 203 illustrated in FIG. 48 is calculated as follows.

A 3=(9.5×6)×L=57L

[0546] As is obvious in view of comparison among the above-mentionedareas A1, A2 and A3, the area A2 of the liquid crystal display device202 including a linear data line, a zigzag-shaped common electrode and azigzag-shaped pixel electrode is smaller than the area A1 of the liquidcrystal display device 201 including a linear data line, a linear commonelectrode and a linear pixel electrode, whereas the area A3 of theliquid crystal display device 203 including a zigzag-shaped data line, azigzag-shaped common electrode and a zigzag-shaped pixel electrode isequal to the area A1.

[0547] This means that it is possible to increase an aperture ratio bydesigning the data line 124 to be zigzag-shaped, in comparison with aliquid crystal display device including a linear data line. This isbecause, in the liquid crystal display device 202 including a lineardata line, a zigzag-shaped common electrode and a zigzag-shaped pixelelectrode, a distance along the line XXXX VII-XXXX VII in FIG. 46between the data line 124 located at the left and the pixel electrode127 located adjacent to the data line 124 is longer than the same inFIG. 48 by 7.5 μm, and hence, an interval between the common electrode126 and the pixel electrode 127 is decreased by a length of 7.5 μm/Xwhere X indicates the number of openings, resulting in that an area ofthe openings is decreased accordingly.

[0548] The liquid crystal display device 100 in accordance with thefourth embodiment can be fabricated in accordance with the same methodas the method of fabricating the liquid crystal display device 10 inaccordance with the first embodiment. Specifically, since the data line124, the common electrode 126 and the pixel electrode 127 in the liquidcrystal display device 100 are formed to be zigzag-shaped, a pattern forforming them is changed so as to define the zigzag-shaped data line 124,the zigzag-shaped common electrode 126 and the zigzag-shaped pixelelectrode 127. The steps for fabricating the liquid crystal displaydevice 100, other than the step of patterning the data line 124, thecommon electrode 126 and the pixel electrode 127, remain unchanged.

[0549] Hereinbelow are explained the parts constituting the liquidcrystal display device 100 in accordance with the fourth embodiment, andvariants thereof.

[0550] The number of inflection of the data line 124, the commonelectrode 126 and the pixel electrode 127 per a pixel may be selectedfrom any number, unless it is an odd number. This is to ensure that aregion in which liquid crystal molecules are twisted in a clockwisedirection is equal in both the number and an area to a region in whichliquid crystal molecules are twisted in a counter-clockwise direction.This enhances symmetry in a viewing angle. Accordingly, the number ofinflection is limited to an odd number such as 1, 3 or 5. As long as thenumber of inflection is an odd number, one (1) or any number equal to orgreater than three (3) may be selected as the number of inflection ofthe data line 124, the common electrode 126 and the pixel electrode 127.

[0551] The smaller the number of inflection is, the higher an apertureratio is, however, the smaller the number of inflection is, more easilya bending pattern can be seen. In addition, since the black matrix layer117 has to be designed to follow the inflection of the data line 124,the common electrode 126 and the pixel electrode 127, it would be moredifficult to pattern the black matrix layer 117, if the data line 124,the common electrode 126 and the pixel electrode 127 had a smallernumber of inflections.

[0552] To the contrary, the greater the number of inflection is, morelikely a bending pattern looks like a line, and the black matrix layercould be fabricated in the form of a thinner line. However, the greaternumber of inflection would make an aperture ratio smaller.

[0553] In view of the above-mentioned matters, the inventors hadconducted the experiments to an optimal number N of inflection in thedata line 124, the common electrode 126 and the pixel electrode 127. Theoptimal number N is determined so as to satisfy the following inequality(A).

30≦L/(N+1)≦40  (A)

[0554] L indicates a length of an opening in a unit of micrometers (μm).See FIG. 42A.

[0555] The black matrix layer 117 may be designed to be linear orzigzag-shaped. In particular, when the black matrix layer 117 is formedto be zigzag-shaped, it is preferable that the black matrix layer 117has a zigzag shape designed in accordance with a zigzag shape of thedata line 124. Though a linear black matrix layer can be fabricated morereadily than a zigzag-shaped black matrix layer, the zigzag-shaped blackmatrix layer 117 would increase an aperture ratio of the liquid crystaldisplay device 100.

[0556] As illustrated in FIG. 50, when viewed in a plan view, it ispreferable that both a distance between a left end of the black matrixlayer 117 and a right end of the data line 124 and a distance between aright end of the black matrix layer 117 and a left end of the data line124 are always equal to or longer than 4 micrometers (μm).

[0557] The reason therefor is explained hereinbelow.

[0558] A distance between a surface of the black matrix layer 117,facing the liquid crystal layer 113, and a surface of the data line 124,facing the liquid crystal layer 113, is usually in the range of 3 to 4micrometers. With reference to FIG. 50, assuming that an angle formedbetween a line connecting a left end of the black matrix layer 117 to aright end of the data line 124, and a surface of the substrate isexpressed as “α”, an angle α at which incident light coming from a sideof the black matrix layer is all reflected is equal to about 45 degrees.Hence, when the above-mentioned distance between a surface of the blackmatrix layer 117, facing the liquid crystal layer 113, and a surface ofthe data line 124, facing the liquid crystal layer 113 is maximum, thatis, equal to 4 micrometers, it would be possible to solve the problemthat a light obliquely entering in the vicinity of one of ends of thedata line 124 passes over the black matrix layer 117, and causes colormixture in displayed images with the result of reduction inchromaticity, if a distance between a left end of the black matrix layer117 and a right end of the data line 124 is equal to or greater than 4micrometers.

[0559] In order to ensure that a distance between a left end of theblack matrix layer 117 and a right end of the data line 124 and adistance between a right end of the black matrix layer 117 and a leftend of the data line 124 are always equal to or longer than 4micrometers, the black matrix layer 117 and the data line 124 have tooverlap each other anywhere by 4 micrometers or greater. Since theactive device substrate 111 and the opposing substrate 112 are usuallydesigned to have an allowable process margin of 4 micrometers to absorbmisregistration therebetween, it will be necessary for the black matrixlayer 117 and the data line 124 to have a width equal to or greater than8 micrometers, if the process margin of 4 micrometers is taken intoconsideration.

[0560]FIGS. 51 and 52 illustrate examples of arrangement of the blackmatrix layer 117 in the liquid crystal display device 100 in accordancewith the fourth embodiment.

[0561] In the arrangement illustrated in FIG. 51, the data line 124 isdesigned to have a width of 10 micrometers, the common electrode 126 isdesigned to have a width of 19 micrometers, the common electrode 126having a plurality of comb-teeth is designed to have seven inflections,and the black matrix layer 117 is designed to have a width of 13.5micrometers.

[0562] A width by which the black matrix layer 117 and the data line 124overlap each other is minimized where the common electrode 126 or thedata line 124 is bent, that is, on the line X-X. In the arrangementillustrated in FIG. 51, a minimum width in which the black matrix layer117 and the data line 124 overlap each other is equal to 8 micrometers.

[0563] In the arrangement illustrated in FIG. 52, the data line 124 isdesigned to have a width of 10 micrometers, the common electrode 126 isdesigned to have a width of 19 micrometers, the common electrode 126having a plurality of comb-teeth is designed to have five inflections,and the black matrix layer 117 is designed to have a width of 16micrometers.

[0564] A width by which the black matrix layer 117 and the data line 124overlap each other is minimized where the common electrode 126 or thedata line 124 is bent, that is, on the line X-X. In the arrangementillustrated in FIG. 52, a minimum width in which the black matrix layer117 and the data line 124 overlap each other is equal to 8 micrometers.

[0565] A minimum width of the black matrix layer 117 in the liquidcrystal display device 100 in accordance with the fourth embodiment,such as the above-mentioned minimum width in the arrangementsillustrated in FIGS. 51 and 52, is determined as follows.

[0566]FIG. 53 illustrates a positional relation among the black matrixlayer 117, the data line 124 and the common electrode 126. Withreference to FIG. 53, the equation for determining a minimum width ofthe black matrix layer 117 is determined as follows.

[0567] Assuming that a width of the data line 124 is expresses as “D”, alength of inclined lines when projected into a direction in which thedata line 124 extends is expressed as “LS”, and an angle formed betweena direction in which the data line 124 extends and inclined lines isexpressed as “θ”, a minimum width Dmin of the black matrix layer 117 fordisallowing an oblique light to enter the data line 124 is expressed asfollows.

Dmin=D+LS×tan θ−(D−8)×2[μm]  (B)

[0568] In the examples illustrated in FIGS. 54 and 55, the data line 124is designed to have a width of 10 micrometers, and further designed tobe zigzag-shaped, including linear portions extending in a length-wisedirection Z of the data line 124, as illustrated in FIG. 43B. The dataline 124 in the examples illustrated in FIGS. 54 and 55 has edgeslocated behind by 3 micrometers from each of bottoms of recesses in theinflections of the data line 124 illustrated in FIG. 52. The commonelectrode 126 has edges defined by recesses projecting beyond the dataline 124 by 4.5 micrometers in comparison with the same illustrated inFIG. 52, and projections located at the same position as a position of aprojection of an edge of the common electrode illustrated in FIG. 52.The common electrode 126 having a plurality of comb-teeth is designed tohave a zigzag shape having five (5) inflections. Under theabove-mentioned conditions, the black matrix layer 117 could have awidth of 10 micrometers.

[0569] A width by which the black matrix layer 117 and the data line 124overlap each other is minimized where the common electrode 126 or thedata line 124 is bent, that is, on the line X-X. In the examplesillustrated in FIGS. 54 and 55, a minimum width in which the blackmatrix layer 117 and the data line 124 overlap each other is equal to 8micrometers.

[0570] Comparing to the example illustrated in FIG. 52, the black matrixlayer 117 can have a width reduced by 6 micrometers, ensuring anincrease in an aperture ratio.

[0571] The common electrode 126 illustrated in FIGS. 54 and 55 is bentin such a zigzag pattern as illustrated in FIG. 43A in portions otherthan portions overlapping the pixel electrode 127 and the data line 124.

[0572] The common electrode 126 overlapping the data line 124 has edgesprojecting beyond the data line 124 by 4.5 micrometers. The edges aredesigned to be V-shaped at summits thereof in order to apply asufficient voltage to a display area.

[0573] As mentioned earlier, a minimum width Dmin of the black matrixlayer 117 for disallowing an oblique light to enter the data line 124 isexpressed as follows.

Dmin=D+LS×tan θ−(D−8)×2[μm]  (B)

[0574] In the example of the black matrix layer 117 illustrated in FIG.55, the data line 124 is designed to have edges displaced outwardly ofthe data line 124 by 3 micrometers from bottoms of recesses in theinflections of the data line 124 illustrated in FIG. 52, and at the sametime, summits of the projections in the inflections of the data line 124are displaced by 3 micrometers inwardly of the data line 124, in orderto form linear portions extending in a length-wise direction of the dataline 124.

[0575] As an alternative, as illustrated in FIG. 54, only bottoms ofrecesses in the inflections of the data line 124 illustrated in FIG. 52may be displaced outwardly of the data line 124 by 3 micrometers withthe bottoms of recesses in the inflections of the data line 124 beingnot displaced.

[0576] In such arrangements as mentioned above, the black matrix layer117 may be designed to have a width of 10 micrometers, ensuring anincrease in an aperture ratio, similarly to the example illustrated inFIGS. 54 and 55.

[0577] As illustrated in FIG. 56, the data line 124 is formed in thesame fashion as the data line illustrated in FIG. 52, and floatingelectrodes 181 may be formed in the vicinity of bottoms of recesses inthe inflections of the data line 124. The floating electrodes 181 arecomprised of the first metal layer of which the common electrode line126 is comprised. Such floating electrodes 181 may be used for shieldinglight from the region indicated in FIG. 53, in which case, the blackmatrix layer 117 may be designed to have a width of 10 micrometers,ensuring an increase in an aperture ratio, similarly to the exampleillustrated in FIGS. 54 and 55.

[0578] In addition, as illustrated in FIG. 57, the common electrode 126may be designed to further include projections 182 projecting fromsummits of the inflections of the common electrode 126 overlapping thedata line 124.

[0579]FIG. 58 illustrates a pixel including the above-mentioned commonelectrode 126 having the projections 182. In the illustrated pixel, theprojections 182 fix a location of the disclination occurring at a domainboundary including summits of the projections 182, ensuring stability indisplaying images even if a display screen is pushed by a finger.

[0580] In the liquid crystal display device 100 in accordance with thefourth embodiment, the color layer 118 constituting the opposingsubstrate 112 may be designed to be zigzag-shaped as well as the dataline 124, the common electrode 126 and the pixel electrode 127. Inparticular; when the color layer 118 is formed to be zigzag-shaped, itis preferable that the color layer 118 has a zigzag shape in accordancewith a zigzag shape of the data line 124.

[0581] The liquid crystal display device 100 in accordance with thefourth embodiment may be designed to further include a stabilizationelectrode between a pixel sub-area in which liquid crystal molecules aretwisted in a clockwise direction and a pixel sub-area in which liquidcrystal molecules are twisted in a counter-clockwise direction, in acolumn of each of pixels. The stabilization electrode ensures a stableboundary between the pixel sub-areas, and thereby, stabilize alignmentof liquid crystal molecules. Thus, even if a display screen were rubbedby a finger, a fingerprint would not remain on the display screen,ensuring an increase in clearness in displayed images.

[0582] Though Japanese Patent Application No. 2000-326814, which wasfiled by the assignee of the present application and is not publishedyet, is explained hereinbelow for emphasizing the advantages of thepresent invention, the explanation made hereinbelow does not mean thatthe applicant admits Japanese Patent Application No. 2000-326814 asstatutory prior art to the present invention. Japanese PatentApplication No. 2000-326814 is explained hereinbelow only for thepurpose of better understanding of the present invention.

[0583] Japanese Patent Application No. 2000-326814 suggests a V-shapedcommon electrode and a V-shaped pixel electrode which have a commonauxiliary electrode and a pixel auxiliary electrode extending outwardlyfrom summits of the V-shaped common electrode and the V-shaped pixelelectrode, respectively. Distal ends of the common auxiliary electrodeand the pixel auxiliary electrode overlap the pixel and commonelectrodes.

[0584] However, the above-mentioned V-shaped common and pixel electrodescannot be applied to the liquid crystal display device 100 in accordancewith the fourth embodiment, because the pixel and common electrodes 127and 126 are formed on a common layer in the liquid crystal displaydevice 100. In addition, it would be necessary to prevent an increase inthe number of fabrication steps for applying the V-shaped common andpixel electrodes to the liquid crystal display device 100.

[0585] Hence, in order for the liquid crystal display device 100 toinclude the stabilization electrode ensuring a stable boundary betweenpixel sub-areas, as illustrated in FIG. 59, floating stabilizingelectrodes 140 are formed below and overlapping summits of theinflections of the pixel electrodes 127. Each of the floatingstabilizing electrodes 140 is comprised of the second metal layer, andhence, is not electrically connected to the pixel electrode 127. Each ofthe floating stabilizing electrodes 140 sufficiently overlap the pixelelectrode 127, and extends towards a boundary between the pixelsub-areas.

[0586] Similarly, floating stabilizing electrodes 141 are formed belowand overlapping summits of the inflections of the common electrodes 126.Each of the floating stabilizing electrodes 141 is comprised of thefirst metal layer. Each of the floating stabilizing electrodes 141sufficiently overlap the common electrode 126, and extends towards aboundary between the pixel sub-areas.

[0587] The above-mentioned floating stabilization electrodes 140 and 141ensure that an electric field in each of the pixel sub-areas is directedto a direction in which liquid crystal molecules are twisted, whichfurther ensures stable division of the pixel sub-areas.

[0588]FIG. 60 illustrates the liquid crystal display device 100 to whichthe floating stabilization electrodes 140 and 141 illustrated in FIG. 59are applied.

[0589]FIG. 61 illustrates a TFT region, a pixel region, and a contacthole region of the liquid crystal display device 100 in a singledrawing. The TFT region, the pixel region and the contact hole regionare illustrated as cross-sectional views taken along the lines A-A, B-B,and C-C in FIG. 60, respectively.

[0590] As illustrated in FIG. 61, the liquid crystal display device 100may be designed to include a pixel auxiliary electrode 135 below thefirst film 25 a of the second interlayer insulating film 25. The pixelauxiliary electrode 135 is comprised of the second metal layer, and isformed integrally with the source electrode 130 b of TFT 130.

[0591]FIG. 62B is a plan view of the ITO layer formed in the liquidcrystal display device illustrated in FIG. 60, and FIG. 62A is a planview of the layers other than the ITO layer, formed in the liquidcrystal display device illustrated in FIG. 60. As illustrated in FIGS.62A and 62B, the pixel auxiliary electrode 135 is comprised of a firstportion 135 a and a second portion 135 b overlapping the commonelectrode lines 126 a and 126 b to thereby define a storage capacitybetween the first and second portions 135 a and 135 b, and the commonelectrode lines 126 a and 126 b, and a third portion 135c formed belowthe pixel electrode 127. The third portion 135 c has a zigzag shape, andconnects the first portion 135 a and the second portion 135 b to eachother. The first portion 135 a, the second portion 135 b and the thirdportion 135 c are arranged in the form of “I”.

[0592] Similarly to the first embodiment, the pixel auxiliary electrodes136 a and 135 b in the liquid crystal display device 100 may be designedto have such oblique edges in each of columns such that a relation amonga rubbing direction or a liquid crystal alignment direction defined byrubbing and a direction of an electric field applied across the pixelelectrode 127 (and the pixel auxiliary electrode 135 to which the samevoltage as that of the pixel electrode 127 is applied) and the commonelectrode 126 (and the common electrode lines 126 a and 126 b to whichthe same voltage as that of the common electrode 126 is applied) isdetermined to ensure that the liquid crystal alignment direction wouldoverlap the direction of the electric field, if the liquid crystalalignment direction were rotated in a clockwise direction by a certainacute angle, entirely in a display area surrounded by the pixelelectrode 127 and the common electrode 126, in electrodes locatedadjacent to the pixel sub-area in which liquid crystal molecules aretwisted in a clockwise direction, or such that the above-mentionedrelation is determined to ensure that the liquid crystal alignmentdirection would overlap the direction of the electric field, if theliquid crystal alignment direction were rotated in a counter-clockwisedirection by a certain acute angle, entirely in a display areasurrounded by the pixel electrode 127 and the common electrode 126, inelectrodes located adjacent to the pixel sub-area in which liquidcrystal molecules are twisted in a counter-clockwise direction. Thisstructure corresponds to the reverse-rotation preventing structure 36having been explained in the first embodiment.

[0593] With reference to FIG. 62A, electrodes connected to summits ofthe inflections of the pixel auxiliary electrode 135 c comprised of thesecond metal layer are comprised also of the second metal layer, andhence, are not floating electrodes. Such electrodes are calledstabilization electrodes 142.

[0594] The stabilization electrodes 142 ensure that an electric field ineach of the pixel sub-areas is stably directed to a direction in whichliquid crystal molecules are twisted, which further ensures stabledivision of the pixel sub-areas.

[0595] In the liquid crystal display device illustrated in FIG. 60, thepixel auxiliary electrode 135 comprised of the second metal layer may bedesigned to include the stabilization electrodes 142 outwardly extendingfrom summits of the inflections of the pixel auxiliary electrode 135along a boundary between two pixel sub-areas in which liquid crystalmolecules are rotated in opposite directions. The stabilizationelectrodes 142 are comprised of the second metal layer, and ensuresstable rotation of liquid crystal molecules in each of pixel sub-areas.

[0596] The common auxiliary electrode comprised of the second metallayer also ensures stable rotation of liquid crystal molecules in eachof pixel sub-areas.

[0597] The liquid crystal display device 100 in accordance with thefourth embodiment may be applied to a liquid crystal display deviceillustrated in FIG. 42B, that is, a liquid crystal display device inwhich an opening of the active device substrate extends in a directionperpendicular to a direction in which the data line 124 extends.

[0598] With respect to such a liquid crystal display device asillustrated in FIG. 42A, that is, a liquid crystal display device inwhich an opening of the active device substrate extends in the samedirection as a direction in which the data line 124 extends, liquidcrystal is vertically poured thereinto, whereas with respect to such aliquid crystal display device as illustrated in FIG. 42B, that is, aliquid crystal display device in which an opening of the active devicesubstrate extends in a direction perpendicular to a direction in whichthe data line 124 extends, liquid crystal is horizontally pouredthereinto. In the latter case, the data line 124 is formed to be linear,and a gate line defining a gate electrode is formed in a zigzag shape.

[0599] [Fifth Embodiment]

[0600]FIG. 63A is a cross-sectional view of an in-plane switching modeactive matrix type liquid crystal display device 180 in accordance withthe fifth embodiment of the present invention, and corresponds to FIG.41, that is, a cross-sectional view of the liquid crystal display device100 in accordance with the third embodiment.

[0601] In the liquid crystal display device 100 in accordance with thethird embodiment, the pixel electrode 127 as well as the commonelectrode 126 is formed on the second film 125 b of the secondinterlayer insulating film 125.

[0602] In the liquid crystal display device 180 in accordance with thefifth embodiment, the pixel electrode 127 is formed of the second metallayer on the first interlayer insulating film 123, similarly to theliquid crystal display device 80 in accordance with the secondembodiment. Since the pixel electrode 127 is comprised of the secondmetal layer, the liquid crystal display device 180 in accordance withthe fifth embodiment has a smaller aperture ratio than the same in theliquid crystal display device 10 in accordance with the firstembodiment. However, since the pixel electrode 127 is comprised of alayer different from a layer of which the common electrode 126 isformed, the pixel electrode 127 and the common electrode 126 would notbe short-circuited each other, ensuring enhancement in a fabricationyield.

[0603] In addition, it is possible to form a storage capacity betweenthe pixel electrode 127 comprised of the second metal layer and thecommon electrode lines 126 a and 126 b both comprised of the first metallayer. This ensures an increase in a total storage capacity of theliquid crystal layer 113, and stabilization in displaying images.

[0604] As mentioned earlier, the common electrode 126 may includestabilization electrodes extending outwardly from summits of theinflections of the common electrode 126 along a boundary between a pixelsub-area in which liquid crystal molecules are twisted in a clockwisedirection and a pixel sub-area in which liquid crystal molecules aretwisted in a counter-clockwise direction, in which case, thestabilization electrode may be comprised of the ITO layer of which thecommon electrode 126 is comprised. Similarly, the pixel electrode 127may include stabilization electrodes extending outwardly from summits ofthe inflections of the pixel electrode 127 along a boundary between apixel sub-area in which liquid crystal molecules are twisted in aclockwise direction and a pixel sub-area in which liquid crystalmolecules are twisted in a counter-clockwise direction, in which case,the stabilization electrode may be comprised of the ITO layer of whichthe pixel electrode 127 is comprised. These stabilization electrodesensure stabilization in rotation of liquid crystal molecules at theboundary of pixel sub-areas.

[0605] [Sixth Embodiment]

[0606]FIG. 63B is a cross-sectional view of an in-plane switching modeactive matrix type liquid crystal display device 185 in accordance withthe sixth embodiment of the present invention, and corresponds to FIG.41, that is, a cross-sectional view of the liquid crystal display device100 in accordance with the third embodiment.

[0607] In the liquid crystal display device 100 in accordance with thethird embodiment, the first film 125 a which constitutes the secondinterlayer insulating film 125 together with the second film 125 b isformed all over a pixel area. In contrast, the second film 125 b may beformed only below the common electrode 126 overlapping the data line124.

[0608] In a display area of a pixel, the common electrode 126 iscomprised of the first metal layer of which the gate electrode isformed, in an area other than an area in which the common electrode 126is composed of transparent metal, overlapping the data line 124.

[0609] In accordance with the sixth embodiment, it is no longernecessary to form the second film 125 b in a large area more thannecessary, and thereby, it would be possible to prevent an increase in aparasitic capacity between the common electrode 126 and the data line124.

[0610] The pixel electrode 127 may be formed on the first interlayerinsulating film 123 together with the data line 124.

[0611] Since the common electrode 126 is comprised of the first metallayer on the first interlayer insulating film 123 in an area other thanan area in which the common electrode 126 is composed of a transparentmetal film formed on the second film 125 b, the in-plane switching modeliquid crystal display device 185 in accordance with the sixthembodiment has a smaller aperture ratio than that of the liquid crystaldisplay device 100 in accordance with the fourth embodiment. However,since the common electrode 126 is comprised of a layer different from alayer of which the pixel electrode 127 is formed, the common electrode126 and the pixel electrode 127 would not be short-circuited each other,ensuring enhancement in a fabrication yield.

[0612] The stabilization electrode to be formed between a pixel sub-areawhere liquid crystal molecules are twisted in a clockwise direction anda pixel sub-area where liquid crystal molecules are twisted in acounter-clockwise direction can be designed to extend outwardly fromsummits of the inflections of the pixel electrode 127 and the commonelectrode 126, similarly to the fifth embodiment, since the pixelelectrode 127 is formed on a layer different from a layer on which thecommon electrode 126 is formed.

[0613] The in-plane switching mode active matrix type liquid crystaldisplay device 185 in accordance with the sixth embodiment can increasean aperture ratio, similarly to the liquid crystal display device 10 inaccordance with the first embodiment.

[0614] [Seventh Embodiment]

[0615] A liquid crystal display device in accordance with the seventhembodiment has the same structure as that of any one of the liquidcrystal display devices in accordance with the first to sixthembodiments except that the liquid crystal display device in accordancewith the seventh embodiment is designed not to include a color layer tobe formed as a part of the opposing substrate. Hence, the seventhembodiment presents an in-plane switching mode active matrix type liquidcrystal display device which displays images in black and white.

[0616] The liquid crystal display device in accordance with the seventhembodiment having the above-mentioned structure has a high light-useefficiency, ensuring high brightness at low power consumption.

[0617] [Eighth Embodiment]

[0618] In the above-mentioned first to seventh embodiments, the colorlayer and the black matrix layer are formed as parts of the opposingsubstrate. In an in-plane switching mode active matrix type liquidcrystal display device in accordance with the eighth embodiment, a colorlayer, a black matrix layer, or both a color layer and a black matrixlayer is(are) not formed as a part of an opposing substrate, but formedas a part of an active device substrate.

[0619] By forming a color layer, a black matrix layer, or both a colorlayer and a black matrix layer as a part of an active device substrate,it would be possible to increase an accuracy in registration betweenthose layers and parts having been already formed in the active devicesubstrate, such as the data line, which ensures that a width of theblack matrix layer and other layers can be reduced, and an apertureratio can be further enhanced.

[0620] In the first, second, fourth or fifth embodiment, a color layerand/or a black matrix layer formed as a part of the active devicesubstrate may be covered with an organic film constituting the secondinterlayer insulating film. The organic film would prevent impuritiescontained in a color layer and/or a black matrix layer formed in theactive device substrate, from eluting into the liquid crystal layer,ensuring enhancement in reliability.

[0621] In the first, second, fourth or fifth embodiment, when the secondinterlayer insulating film is comprised of a first film comprised of aninorganic film and a second film comprised of an organic film, a colorlayer and/or a black matrix layer may be sandwiched between the firstand second films. The organic film would prevent impurities contained ina color layer and/or a black matrix layer formed in the active devicesubstrate, from eluting into the liquid crystal layer, and furtherprevent the active device substrate from being influenced by movement ofelectric charges and/or ions in the color layer, ensuring enhancement inreliability.

[0622]FIGS. 64 and 65 illustrate the in-plane switching mode activematrix type liquid crystal display device in accordance with the eighthembodiment, which corresponds to the liquid crystal display device 100in accordance with the fourth embodiment, illustrated in FIGS. 40 and41, and in which the second interlayer insulating film 125 is comprisedof the first film 125 a comprised of an inorganic film and the secondfilm 125 b comprised of an organic film, and the color layer 118 and theblack matrix layer 117 are sandwiched between the first film 125 a andthe second film 125 b. FIG. 64 is a plan view of the liquid crystaldisplay device in accordance with the eighth embodiment, and FIG. 65 isa cross-sectional view taken along the line XXXXXX V-XXXXXX V in FIG.64.

[0623] [Ninth Embodiment]

[0624] The liquid crystal display device 10 in accordance with the firstembodiment, the liquid crystal display device 80 in accordance with thesecond embodiment, the liquid crystal display device 85 in accordancewith the third embodiment, the liquid crystal display device 100 inaccordance with the fourth embodiment, the liquid crystal display device180 in accordance with the fifth embodiment, the liquid crystal displaydevice 185 in accordance with the sixth embodiment, the liquid crystaldisplay device in accordance with the seventh embodiment or the liquidcrystal display device in accordance with the eighth embodiment may beapplied an electronic device. Hereinbelow, some examples are explained.

[0625]FIG. 66 is a block diagram of a portable communication device 250to which one of the liquid crystal display devices 10, 80, 85, 100, 180and 185 is applied. In the portable communication device 250, the liquidcrystal display devices 10, 80, 85, 100, 180 or 185, the liquid crystaldisplay device in accordance with the seventh embodiment or the liquidcrystal display device in accordance with the eighth embodiment is usedas a part of a later mentioned liquid crystal panel 265.

[0626] The portable communication terminal 250 is comprised of a displayunit 268 including a liquid crystal panel 265, a backlight emitter 266,and an image signal processor 267, a controller 269 controllingoperation of the parts constituting the portable communication terminal250, a memory 271 storing a program to be executed by the controller 269and various data, a communication unit 272 which makes datacommunication, an input device 273 comprised of a By keyboard or apointer, and a power source 274 supplying power to the above-mentionedparts constituting the portable communication terminal 250.

[0627] The liquid crystal panel 265 including the liquid crystal displaydevice in accordance with one of the above-mentioned embodimentsenhances an aperture ratio in the display unit 268, and further enhancesa brightness in the display unit 268.

[0628] The liquid crystal panel 265 including the liquid crystal displaydevice 10, 80, 85, 100, 180 or 185 may be applied to a monitor of aportable personal computer, a note type personal computer, or a desktoptype personal computer.

[0629]FIG. 67 is a block diagram of a cellular phone 275 to which one ofthe liquid crystal display devices 10, 80, 85, 100, 180 and 185 isapplied.

[0630] The cellular phone 275 is comprised of a display unit 276including a liquid crystal panel 265, a backlight emitter 266, and animage signal processor 267, a controller 277 controlling operation ofthe parts constituting the cellular phone 275, a memory 278 storing aprogram to be executed by the controller 277 and various data, a radiosignal receiver 279, a radio signal transmitter 281, an input device 282comprised of a keyboard or a pointer, and a power source 283 supplyingpower to the above-mentioned parts constituting the cellular phone 275.

[0631] The liquid crystal panel 265 including the liquid crystal displaydevice in accordance with one of the above-mentioned embodimentsenhances an aperture ratio in the display unit 276, and further enhancesa brightness in the display unit 276.

[0632] In the above-mentioned first to ninth embodiments, the parts bywhich the present invention is characterized are mainly explained, andparts known to those skilled in the art are not explained in detail.However, it should be noted that the latter can be readily understood tothose skilled in the art without detailed explanation.

[0633] While the present invention has been described in connection withcertain preferred embodiments, it is to be understood that the subjectmatter encompassed by way of the present invention is not to be limitedto those specific embodiments. On the contrary, it is intended for thesubject matter of the invention to include all alternatives,modifications and equivalents as can be included within the spirit andscope of the following claims.

[0634] The entire disclosure of Japanese Patent Applications Nos.2001-048473 and 2001-350620 filed on Feb. 23, 2001 and Nov. 15, 2001,respectively, including specification, claims, drawings and summary isincorporated herein by reference in its entirety.

What is claimed is:
 1. An in-plane switching mode active matrix typeliquid crystal display device comprising: (a) a first substrate; (b) asecond substrate located opposing said first substrate; and (c) a liquidcrystal layer sandwiched between said first and second substrates,wherein said first substrate includes: (a1) a thin film transistorhaving a gate electrode, a drain electrode and a source electrode; (a2)a pixel electrode each associated to a pixel to be driven; (a3) a commonelectrode to which a reference voltage is applied; (a4) data lines; (a5)a scanning line; and (a6) common electrode lines, said gate electrode iselectrically connected to said scanning line, said drain electrode iselectrically connected to said data lines, said source electrode iselectrically connected to said pixel electrode, and said commonelectrode is electrically connected to said common electrode lines,molecular axes of liquid crystal in said liquid crystal layer arerotated in a plane parallel with said first substrate by an electricfield substantially parallel with a plane of said first substrate and tobe applied between said pixel electrode and said common electrode, tothereby display certain images, said common electrode is composed oftransparent material, and are formed on a layer located closer to saidliquid crystal layer than said data lines, said common electrodeentirely overlaps said data lines with an insulating layer beingsandwiched therebetween except an area where said data lines are locatedin the vicinity of said scanning line, said in-plane switching modeactive matrix type liquid crystal display device further includes alight-impermeable layer in an area where said common electrode entirelyoverlaps the data lines, said light-impermeable layer is formed on saidsecond substrate or on said first substrate such that saidlight-impermeable layer and said liquid crystal layer are located at thesame side with respect to said data lines and that saidlight-impermeable layer faces said data lines, said light-impermeablelayer is comprised of a black matrix layer or multi-layered colorlayers, said black matrix layer or said multi-layered color layers has awidth smaller than a width of said common electrode overlapping saiddata lines.
 2. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 1, wherein said commonelectrode is electrically connected to said common electrode linesthrough a contact hole in each of pixels.
 3. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim1, wherein said black matrix layer facing said data lines is formed in aline.
 4. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 3, wherein a distance along asubstrate between one of ends of said black matrix layer facing saiddata lines and an end of said data lines, located opposite to said oneof ends of said black matrix layer, is equal to or greater than 4 μm ina cross-section taken along a plane perpendicular to a direction inwhich said data lines extend.
 5. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 3,wherein said black matrix layer is formed on said second substrate, andsaid black matrix layer facing said data lines overlaps said data linesanywhere by 4 μm or greater, when viewed from above.
 6. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, wherein one of said first and second substrates iscomprised further of a color layer formed in a line.
 7. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, further comprising a reverse-rotation preventingstructure in a sub pixel area in which all liquid crystal molecules arerotated in the same direction, for preventing liquid crystal moleculesfrom rotating in a direction opposite to said same direction, saidreverse-rotation preventing structure including an auxiliary electrodeto which a voltage equal to a voltage of at least one of said pixelelectrode and said common electrode is applied such that an initialalignment orientation of liquid crystal molecules overlaps a directionof an electric field generated in said sub pixel area in all sub-areasin said sub pixel areas, if said initial alignment orientation rotatesby an acute angle.
 8. The in-plane switching mode active matrix typeliquid crystal display device as set forth in claim 1, furthercomprising an interlayer insulating film formed below said commonelectrode overlapping said data lines, said interlayer insulating filmbeing comprised of an upper layer and a lower layered, said upper layerbeing formed only below a portion of said common electrode which portionoverlaps said data lines.
 9. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 1, wherein saidcommon electrode is wider than said data lines at opposite ends in awidth-wise direction thereof by 1.5 μm or greater.
 10. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, wherein said black matrix layer has a width smallerthan a width of said data lines, and overlaps said data lines in itsentire length.
 11. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 1, wherein said blackmatrix layer is formed on said second substrate, and said black matrixlayer facing said data lines has a width equal to or greater than 6 μm.12. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 1, wherein said black matrix layeroverlaps said scanning line and a region therearound, and an areasandwiched between said scanning line and said pixel electrode and aregion therearound.
 13. The in-plane switching mode active matrix typeliquid crystal display device as set forth in claim 1, wherein saidpixel electrode is composed of transparent material.
 14. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, wherein said common electrode and said pixel electrodeare formed in a common layer.
 15. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 1,further comprising an interlayer insulating layer formed in a layerlocated immediately below said common electrode, and a pixel auxiliaryelectrode comprised of a single or a plurality of layer(s) formed belowsaid interlayer insulating layer, said pixel auxiliary electrode beingelectrically connected to said source electrode, and being kept at avoltage equal to a voltage of said pixel electrode, said pixel auxiliaryelectrode being composed of opaque metal.
 16. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 15, wherein said pixel auxiliary electrode is at least partiallyformed below said pixel electrode formed in a layer in which said commonelectrode is formed, and having a plurality of comb-teeth.
 17. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 1, further comprising an interlayer insulatinglayer formed in a layer located immediately below said common electrode,and a common auxiliary electrode comprised of a single or a plurality oflayer(s) formed below said interlayer insulating layer, said commonauxiliary electrode being electrically connected to said commonelectrode lines, and being kept at a voltage equal to a voltage of saidcommon electrode, said common auxiliary electrode being composed ofopaque metal.
 18. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 17, wherein said commonauxiliary electrode is formed below said common electrode having aplurality of comb-teeth.
 19. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 1, wherein ascanning line terminal, a data line terminal and a common electrode lineterminal are covered with or composed of a material of which said commonelectrode comprised of transparent electrodes are composed.
 20. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 15, further comprising a reverse-rotationpreventing structure in a sub pixel area in which all liquid crystalmolecules are rotated in the same direction, for preventing liquidcrystal molecules from rotating in a direction opposite to said samedirection, at least a part of edges of said pixel auxiliary electrodesand said common electrode lines being formed oblique such that aninitial alignment orientation of liquid crystal molecules overlaps adirection of an electric field generated in said sub pixel area in allsub-areas in said sub pixel areas, if said initial alignment orientationrotates by an acute angle.
 21. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 1, furthercomprising a passivation film covering said common electrode therewith.22. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 21, further comprising apassivation film covering said pixel electrode therewith.
 23. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 1, wherein said first substrate is formed with oneof a first contact hole electrically connecting said pixel electrode tosaid source electrode, and a second contact hole electrically connectingsaid common electrode to said common electrode lines, said first andsecond contact holes being square or rectangular in shape, and having aside having a length equal to or greater than 6 μm.
 24. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, wherein said first substrate is formed with one of afirst contact hole electrically connecting said pixel electrode to saidsource electrode, and a second contact hole electrically connecting saidcommon electrode to said common electrode lines, said first and secondcontact holes being covered at inner surfaces thereof with a metal film.25. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 1, wherein said pixel electrode isformed of a second metal layer of which said data lines are formed. 26.The in-plane switching mode active matrix type liquid crystal displaydevice as set forth in claim 25, wherein said pixel electrode is formedof a second metal layer of which said drain electrode is formed, in anarea in which an image is displayed, and a portion of said commonelectrode other than a portion composed of transparent metal andoverlapping said data lines is formed of a first metal layer of whichsaid gate electrode is formed.
 27. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 26,further comprising an interlayer insulating film sandwiched between saiddata lines and said common electrode overlapping said data lines andcomposed of transparent metal, said interlayer insulating film beingformed only below said common electrode.
 28. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim1, further comprising an interlayer insulating film sandwiched betweensaid data lines and said common electrode overlapping said data linesand composed of transparent metal, said interlayer insulating film beingcomprised of an inorganic film.
 29. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 1,further comprising an interlayer insulating film sandwiched between saiddata lines and said common electrode overlapping said data lines andcomposed of transparent metal, said interlayer insulating film beingcomprised of an organic film.
 30. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 1,further comprising an interlayer insulating film sandwiched between saiddata lines and said common electrode overlapping said data lines andcomposed of transparent metal, said interlayer insulating film beingcomprised of a first film comprised of an inorganic film and a secondfilm comprised of an organic film and covering said first filmtherewith.
 31. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 28, wherein said inorganicfilm is comprised of one of a silicon nitride film, an inorganicpolysilazane film, a silicon oxide film, and a multi-layered structureincluding two or more of them.
 32. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 30,wherein said inorganic film is comprised of one of a silicon nitridefilm, an inorganic polysilazane film, a silicon oxide film, and amulti-layered structure including two or more of them.
 33. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 29, wherein said organic film is comprised of one of aphotosensitive acrylic resin film, a photosensitive polyimide film, abenzocyclobutene (BCB) film, an organic polysilazane film, and asiloxane film.
 34. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 30, wherein said organicfilm is comprised of one of a photosensitive acrylic resin film, aphotosensitive polyimide film, a benzocyclobutene (BCB) film, an organicpolysilazane film, and a siloxane film.
 35. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim30, wherein said first film is comprised of a silicon nitride film andsaid second film is comprised of one of a photosensitive acrylic resinfilm and a photosensitive polyimide resin film.
 36. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, wherein said common electrode composed of transparentmetal and overlapping said data lines further overlaps an area betweensaid scanning line and said common electrode lines.
 37. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 1, wherein said common electrode composed of transparentmetal and overlapping said data lines further overlaps a channel regionof said thin film transistor.
 38. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 15,wherein a storage capacity is formed between said common electrode linescomprised of a first metal layer of which said gate electrode is formed,and a pixel auxiliary electrode comprised of a second metal layer ofwhich said drain electrode is formed.
 39. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim1, wherein said common electrode lines are formed on opposite sides oron either side of said scanning line along said scanning line in a planview of each of pixels.
 40. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 1, furthercomprising a light-impermeable layer electrically connected to saidcommon electrode and formed below said data lines in an area where saiddata lines are not overlapped by both said black matrix layer and saidmulti-layered color layers, and said common electrode do not overlapsaid data lines.
 41. The in-plane switching mode active matrix typeliquid crystal display device as set forth in claim 1, wherein said gateelectrode is comprised of a first metal layer and said drain electrodeis comprised of a second metal layer, said first and second metal layersbeing comprised of one of a chromium layer, an aluminum layer, atitanium layer, a molybdenum layer, a tungsten layer, and amulti-layered film including one or more of these layers.
 42. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 1, wherein said pixel electrode and said sourceelectrode or said pixel auxiliary electrode formed of a second metallayer are electrically connected to each other through a first contacthole in each of pixels at one of upper and lower sides when viewed fromabove, and said common electrode and said common electrode lines formedof a first metal layer are electrically connected to each other througha second contact hole in each of pixels at the other of upper and lowersides when viewed from above.
 43. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 1,wherein said transparent electrode is composed of Indium-Tin-Oxide(ITO).
 44. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 25, wherein a storage capacity isformed between said common electrode lines comprised of a first metallayer of which said gate electrode is formed, and a pixel electrodecomprised of a second metal layer of which said drain electrode isformed.
 45. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 30, further comprising aninterlayer insulating film formed between said data lines and saidcommon electrode, said interlayer insulating film being comprised of afirst film comprised of an inorganic film, and a second film coveringsaid first film therewith and comprised of an organic film, said firstfilm having a thickness equal to or greater than 0.25 μm.
 46. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 1, further comprising a color layer formed on saidfirst substrate.
 47. The in-plane switching mode active matrix typeliquid crystal display device as set forth in claim 1, furthercomprising a black matrix layer formed on said first substrate.
 48. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 46, further comprising a black matrix layer formedon said first substrate.
 49. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 47, furthercomprising an interlayer insulating film formed between said data linesand said common electrode, said interlayer insulating film including atleast an organic film, said black matrix or color layer being coveredwith said organic film.
 50. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 48, furthercomprising an interlayer insulating film formed between said data linesand said common electrode, said interlayer insulating film including atleast an organic film, said black matrix or color layer being coveredwith said organic film.
 51. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 47, furthercomprising an interlayer insulating film formed between said data linesand said common electrode, said interlayer insulating film beingcomprised of a first film comprised of an inorganic film, and a secondfilm covering said first film therewith and comprised of an organicfilm, said color or black matrix layer being sandwiched between saidfirst and second films.
 52. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 48, furthercomprising an interlayer insulating film formed between said data linesand said common electrode, said interlayer insulating film beingcomprised of a first film comprised of an inorganic film, and a secondfilm covering said first film therewith and comprised of an organicfilm, said color or black matrix layer being sandwiched between saidfirst and second films.
 53. An in-plane switching mode active matrixtype liquid crystal display device comprising: (a) a first substrate;(b) a second substrate located opposing said first substrate; and (c) aliquid crystal layer sandwiched between said first and secondsubstrates, wherein said first substrate includes: (a1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode; (a2) a pixel electrode each associated to a pixel to bedriven; (a3) a common electrode to which a reference voltage is applied;(a4) data lines; (a5) a scanning line; and (a6) common electrode lines,said gate electrode is electrically connected to said scanning line,said drain electrode is electrically connected to said data lines, saidsource electrode is electrically connected to said pixel electrode, andsaid common electrode is electrically connected to said common electrodelines, said pixel electrode is in a zigzag form and almost equallyspaced away from adjacent ones, said common electrode is in a zigzagform and almost equally spaced away from adjacent ones, two-directionalelectric fields almost parallel with a surface of said first substrateare applied across said pixel electrode and said common electrode, saidin-plane switching mode active matrix type liquid crystal display deviceincludes a first sub pixel area to which an electric field having afirst direction is applied and in which molecular axes of liquid crystalin said liquid crystal layer are rotated in a first rotational directionin a plane parallel with a surface of said first substrate, and a secondsub pixel area to which an electric field having a second direction isapplied and in which said molecular axes are rotated in a secondrotational direction which is different from said first rotationaldirection, in a plane parallel with a surface of said first substrate,said common electrode is composed of transparent material, and is formedon a layer located closer to said liquid crystal layer than said datalines, said common electrode entirely overlaps said data lines with aninsulating layer being sandwiched therebetween except an area where saiddata lines are located in the vicinity of said scanning line, saidin-plane switching mode active matrix type liquid crystal display devicefurther includes a light-impermeable layer in an area where said commonelectrode entirely overlaps the data lines, said light-impermeable layeris formed on said second substrate or on said first substrate such thatsaid light-impermeable layer and said liquid crystal layer are locatedat the same side with respect to said data lines and that saidlight-impermeable layer faces said data lines, said light-impermeablelayer is comprised of a black matrix layer or multi-layered colorlayers, said black matrix layer or said multi-layered color layers has awidth smaller than a width of said common electrode overlapping saiddata lines, said data lines extend in a zigzag along said pixelelectrode.
 54. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, wherein said commonelectrode is electrically connected to said common electrode linesthrough a contact hole in each of pixels.
 55. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 53, wherein said data lines, said common electrode and said pixelelectrode are bent by one in each of pixels.
 56. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 53, wherein said data lines, said common electrode and said pixelelectrode are bent by an odd number equal to or greater than 3 in eachof pixels.
 57. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, wherein said datalines, said common electrode and said pixel electrode are bent by N ineach of pixels, said N being defined in accordance with the equation(A): 30[μm]≦L/(N+1)[μm]≦40[μm]  (A)wherein L indicates a length of anopening.
 58. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, wherein said blackmatrix layer facing said data lines is formed in a line.
 59. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 53, wherein said black matrix layer facing saiddata lines is formed in a zigzag.
 60. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 53,wherein said black matrix layer facing said data lines is bent in linewith said data lines.
 61. The in-plane switching mode active matrix typeliquid crystal display device as set forth in claim 53, wherein adistance along a substrate between one of ends of said black matrixlayer facing said data lines and an end of said data lines, locatedopposite to said one of ends of said black matrix layer, is equal to orgreater than 4 μm in a cross-section taken along a plane perpendicularto a direction in which said data lines extend.
 62. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 60, wherein a distance along a substrate between one ofends of said black matrix layer facing said data lines and an end ofsaid data lines, located opposite to said one of ends of said blackmatrix layer, is equal to or greater than 4 μm in a cross-section takenalong a plane perpendicular to a direction in which said data linesextend.
 63. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, wherein said blackmatrix layer is formed on said second substrate, and said black matrixlayer facing said data lines overlaps said data lines anywhere by 4 μmor greater, when viewed from above.
 64. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim59, wherein said black matrix layer is formed on said second substrate,and said black matrix layer facing said data lines overlaps said datalines anywhere by 4 μm or greater, when viewed from above.
 65. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 53, wherein one of said first and secondsubstrates is comprised further of a color layer formed in a line. 66.The in-plane switching mode active matrix type liquid crystal displaydevice as set forth in claim 53, wherein one of said first and secondsubstrates is comprised further of a color layer formed in a zigzag. 67.The in-plane switching mode active matrix type liquid crystal displaydevice as set forth in claim 66, wherein said color layer is bent inline with said data lines.
 68. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 53, furthercomprising a reverse-rotation preventing structure in a sub pixel areain which all liquid crystal molecules are rotated in the same direction,for preventing liquid crystal molecules from rotating in a directionopposite to said same direction, said reverse-rotation preventingstructure including an auxiliary electrode to which a voltage equal to avoltage of at least one of said pixel electrode and said commonelectrode is applied such that an initial alignment orientation ofliquid crystal molecules overlaps a direction of an electric fieldgenerated in said sub pixel area in all sub-areas in said sub pixelareas, if said initial alignment orientation rotates by an acute angle.69. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 53, further comprising an isolatedfloating electrode composed of a layer of which both said gate electrodeand said drain electrode are composed, said isolated floating electrodeoverlapping said common or pixel electrode at bending portions of saidzigzag-shaped common or pixel electrode with said insulating layer beingsandwiched therebetween, and having an extension extending in adirection in which said bending portions project, along an boundarybetween said first and second sub pixel areas.
 70. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 53, wherein said zigzag-shaped data lines includes linearportions inclining towards the left and right from a direction in whichsaid data lines extend.
 71. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 70, whereinsaid black matrix layer is formed on said second substrate, and saidblack matrix layer facing said data lines and formed in a line has awidth greater anywhere than a minimum width Dmin defined by thefollowing equation: Dmin=D+LS×tan θ−(D−8)×2[μm]wherein D indicates awidth of said data lines, LS indicates a length obtained when saidlinear portions are projected towards said direction in which said datalines extend, and θ indicates an angle formed between said direction inwhich said data lines extend and said linear portions.
 72. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 53, wherein said zigzag-shaped data lines includes firstlinear portions extending in parallel with a direction in which saiddata lines extend, and second linear portions inclining towards the leftand right from said direction in which said data lines extend.
 73. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 72, wherein said black matrix layer is formed onsaid second substrate, and said black matrix layer facing said datalines and formed in a line has a width greater anywhere than a minimumwidth Dmin defined by the following equation: Dmin=D+LS×tanθ−(D−8)×2[μm]wherein D indicates a width of said data lines, LSindicates a length obtained when said second linear portions areprojected towards said direction in which said data lines extend, and θindicates an angle formed between said direction in which said datalines extend and said second linear portions.
 74. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 70, further comprising coverages which are fit into recessionsformed at bending portions of said zigzag-shaped data lines.
 75. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 70, further comprising a floatinglight-impermeable film composed of opaque metal, said floatinglight-impermeable film overlapping said data lines at recessions ofbending portions of said data lines.
 76. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim53, further comprising a projection projecting from a bending portion ofeach of said zigzag-shaped common electrode overlapping saidzigzag-shaped data lines.
 77. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 53, whereinsaid common electrode is wider than said data lines at opposite ends ina width-wise direction thereof by 1.5 μm or greater.
 78. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 53, wherein said black matrix layer has a width smallerthan a width of said data lines, and overlaps said data lines in itsentire length.
 79. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, wherein said pixelelectrode is composed of transparent material.
 80. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 53, wherein said common electrode and said pixelelectrode are formed in a common layer.
 81. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim53, further comprising an interlayer insulating layer formed in a layerlocated immediately below said common electrode, and a pixel auxiliaryelectrode comprised of a single or a plurality of layer(s) formed belowsaid interlayer insulating layer, said pixel auxiliary electrode beingelectrically connected to said source electrode, and being kept at avoltage equal to a voltage of said pixel electrode, said pixel auxiliaryelectrode being composed of opaque metal.
 82. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 81, wherein said pixel auxiliary electrode is at least partiallyformed below said pixel electrode formed in a layer in which said commonelectrode is formed, and having a plurality of comb-teeth.
 83. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 53, further comprising an interlayer insulatinglayer formed in a layer located immediately below said common electrode,and a common auxiliary electrode comprised of a single or a plurality oflayer(s) formed below said interlayer insulating layer, said commonauxiliary electrode being electrically connected to said commonelectrode lines, and being kept at a voltage equal to a voltage of saidcommon electrode, said common auxiliary electrode being composed ofopaque metal.
 84. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 83, wherein said commonauxiliary electrode is formed below said common electrode having aplurality of comb-teeth.
 85. The in-plane switching mode active matrixtype liquid crystal display device as set forth in claim 82, furthercomprising a reverse-rotation preventing structure in a sub pixel areain which all liquid crystal molecules are rotated in the same direction,for preventing liquid crystal molecules from rotating in a directionopposite to said same direction, at least a part of edges of said pixelauxiliary electrodes and said common electrode lines being formedoblique such that an initial alignment orientation of liquid crystalmolecules overlaps a direction of an electric field generated in saidsub pixel area in all sub-areas in said sub pixel areas, if said initialalignment orientation rotates by an acute angle.
 86. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 82, wherein said zigzag-shaped common and pixelelectrodes define a sub pixel area in which liquid crystal moleculesrotate in two directions in a pixel, some of said pixel auxiliaryelectrodes having a projection projecting from a bending portion of eachof said zigzag-shaped pixel electrode and in a direction in which saidbending portion projects, along a boundary between two sub pixel areasin which liquid crystal molecules rotate in different directions. 87.The in-plane switching mode active matrix type liquid crystal displaydevice as set forth in claim 84, wherein said zigzag-shaped common andpixel electrodes define a sub pixel area in which liquid crystalmolecules rotate in two directions in a pixel, some of said commonauxiliary electrodes having a projection projecting from a bendingportion of each of said zigzag-shaped common electrode, in a directionin which said bending portion projects, along a boundary between two subpixel areas in which liquid crystal molecules rotate in differentdirections, for stabilizing rotation of said liquid crystal moleculesbetween said two sub pixel areas.
 88. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 53,wherein said pixel electrode is formed of a second metal layer of whichsaid data lines are formed.
 89. The in-plane switching mode activematrix type liquid crystal display device as set forth in claim 88,wherein said pixel electrode is formed of a second metal layer of whichsaid drain electrode is formed, in an area in which an image isdisplayed, and a portion of said common electrode other than a portioncomposed of transparent metal and overlapping said data lines is formedof a first metal layer of which said gate electrode is formed.
 90. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 89, further comprising an interlayer insulatingfilm sandwiched between said data lines and said common electrodeoverlapping said data lines and composed of transparent metal, saidinterlayer insulating film being formed only below said commonelectrode.
 91. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, further comprising aninterlayer insulating film sandwiched between said data lines and saidcommon electrode overlapping said data lines and composed of transparentmetal, said interlayer insulating film being comprised of an inorganicfilm.
 92. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 53, further comprising aninterlayer insulating film sandwiched between said data lines and saidcommon electrode overlapping said data lines and composed of transparentmetal, said interlayer insulating film being comprised of an organicfilm.
 93. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 53, further comprising aninterlayer insulating film sandwiched between said data lines and saidcommon electrode overlapping said data lines and composed of transparentmetal, said interlayer insulating film being comprised of a first filmcomprised of an inorganic film and a second film comprised of an organicfilm and covering said first film therewith.
 94. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 91, wherein said inorganic film is comprised of one of a siliconnitride film, an inorganic polysilazane film, a silicon oxide film, anda multi-layered structure including two or more of them.
 95. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 93, wherein said inorganic film is comprised ofone of a silicon nitride film, an inorganic polysilazane film, a siliconoxide film, and a multi-layered structure including two or more of them.96. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 92, wherein said organic film iscomprised of one of a photosensitive acrylic resin film, aphotosensitive polyimide film, a benzocyclobutene (BCB) film, an organicpolysilazane film, and a siloxane film.
 97. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim93, wherein said organic film is comprised of one of a photosensitiveacrylic resin film, a photosensitive polyimide film, a benzocyclobutene(BCB) film, an organic polysilazane film, and a siloxane film.
 98. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 93, wherein said first film is comprised of asilicon nitride film and said second film is comprised of one of aphotosensitive acrylic resin film and a photosensitive polyimide resinfilm.
 99. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 81, wherein a storage capacity isformed between said common electrode lines comprised of a first metallayer of which said gate electrode is formed, and a pixel auxiliaryelectrode comprised of a second metal layer of which said drainelectrode is formed.
 100. The in-plane switching mode active matrix typeliquid crystal display device as set forth in claim 53, wherein saidtransparent electrode is composed of Indium-Tin-Oxide (ITO).
 101. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 88, wherein a storage capacity is formed betweensaid pixel electrode comprised of said second metal layer of which saiddrain electrode is formed, and said common electrode lines comprised ofsaid first metal layer of which said gate electrode is formed.
 102. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 88, wherein said zigzag-shaped common and pixelelectrodes define a sub pixel area in which liquid crystal molecules arerotated in two directions in a pixel, and some of at least one of saidcommon and pixel electrodes have a projection projecting from a bendingportion of each of said zigzag-shaped common electrode, in a directionin which said bending portion projects, along a boundary between two subpixel areas in which liquid crystal molecules rotate in differentdirections, for stabilizing rotation of said liquid crystal moleculesbetween said two sub pixel areas.
 103. The in-plane switching modeactive matrix type liquid crystal display device as set forth in claim93, further comprising an interlayer insulating film formed between saiddata lines and said common electrode, said interlayer insulating filmbeing comprised of a first film comprised of an inorganic film, and asecond film covering said first film therewith and comprised of anorganic film, said first film having a thickness equal to or greaterthan 0.25 μm.
 104. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 53, further comprising acolor layer formed on said first substrate.
 105. The in-plane switchingmode active matrix type liquid crystal display device as set forth inclaim 53, further comprising a black matrix layer formed on said firstsubstrate.
 106. The in-plane switching mode active matrix type liquidcrystal display device as set forth in claim 104, further comprising ablack matrix layer formed on said first substrate.
 107. The in-planeswitching mode active matrix type liquid crystal display device as setforth in claim 105, further comprising an interlayer insulating filmformed between said data lines and said common electrode, saidinterlayer insulating film including at least an organic film, saidcolor or black matrix layer being covered with said organic film. 108.The in-plane switching mode active matrix type liquid crystal displaydevice as set forth in claim 106, further comprising an interlayerinsulating film formed between said data lines and said commonelectrode, said interlayer insulating film including at least an organicfilm, said color or black matrix layer being covered with said organicfilm.
 109. The in-plane switching mode active matrix type liquid crystaldisplay device as set forth in claim 105, further comprising aninterlayer insulating film formed between said data lines and saidcommon electrode, said interlayer insulating film being comprised of afirst film comprised of an inorganic film, and a second film coveringsaid first film therewith and comprised of an organic film, said colorlayer being sandwiched between said first and second films.
 110. Thein-plane switching mode active matrix type liquid crystal display deviceas set forth in claim 106, further comprising an interlayer insulatingfilm formed between said data lines and said common electrode, saidinterlayer insulating film being comprised of a first film comprised ofan inorganic film, and a second film covering said first film therewithand comprised of an organic film, said color layer being sandwichedbetween said first and second films.
 111. An in-plane switching modeactive matrix type liquid crystal display device comprising: (a) a firstsubstrate; (b) a second substrate located opposing said first substrate;and (c) a liquid crystal layer sandwiched between said first and secondsubstrates, wherein said first substrate includes: (a1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode; (a2) a pixel electrode each associated to a pixel to bedriven; (a3) a common electrode to which a reference voltage is applied;(a4) data lines; (a5) a scanning line; and (a6) common electrode lines,said gate electrode is electrically connected to said scanning line,said drain electrode is electrically connected to said data lines, saidsource electrode is electrically connected to said pixel electrode, andsaid common electrode is electrically connected to said common electrodelines, said pixel electrode is in a zigzag form and almost equallyspaced away from adjacent ones; said common electrode is in a zigzagform and almost equally spaced away from adjacent ones, two-directionalelectric fields almost parallel with a surface of said first substrateare applied across said pixel electrode and said common electrode, saidin-plane switching mode active matrix type liquid crystal display deviceincludes a first sub pixel area to which an electric field having afirst direction is applied and in which molecular axes of liquid crystalin said liquid crystal layer are rotated in a first rotational directionin a plane parallel with a surface of said first substrate, and a secondsub pixel area to which an electric field having a second direction isapplied and in which said molecular axes are rotated in a secondrotational direction which is different from said first rotationaldirection, in a plane parallel with a surface of said first substrate,an opening of said first substrate extends in a direction perpendicularto a direction in which said data lines extend, said common electrode iscomposed of transparent material, and is formed on a layer locatedcloser to said liquid crystal layer than said data lines, said commonelectrode entirely overlaps said data lines with an insulating layerbeing sandwiched therebetween except an area where said data lines arelocated in the vicinity of said scanning line, said common electrode iselectrically connected to said common electrode lines through a contacthole in each of pixels, said in-plane switching mode active matrix typeliquid crystal display device further includes a light-impermeable layerin an area where said common electrode entirely overlaps the data lines,said light-impermeable layer is formed on said second substrate or onsaid first substrate such that said light-impermeable layer and saidliquid crystal layer are located at the same side with respect to saiddata lines and that said light-impermeable layer faces said data lines,said light-impermeable layer is comprised of a black matrix layer ormulti-layered color layers, said black matrix layer or saidmulti-layered color layers has a width smaller than a width of saidcommon electrode overlapping said data lines, said data lines extend ina line, a gate line which constitutes said gate electrode extends in azigzag.
 112. An in-plane switching mode active matrix type liquidcrystal display device comprising: (a) a first substrate; (b) a secondsubstrate located opposing said first substrate; and (c) a liquidcrystal layer sandwiched between said first and second substrates,wherein said first substrate includes: (a1) a thin film transistorhaving a gate electrode, a drain electrode and a source electrode; (a2)a pixel electrode each associated to a pixel to be driven; (a3) a commonelectrode to which a reference voltage is applied; (a4) data lines; (a5)a scanning line; and (a6) common electrode lines, said gate electrode iselectrically connected to said scanning line, said drain electrode iselectrically connected to said data lines, said source electrode iselectrically connected to said pixel electrode, and said commonelectrode is electrically connected to said common electrode lines, saidpixel electrode is in a zigzag form and almost equally spaced away fromadjacent ones, said common electrode is in a zigzag form and almostequally spaced away from adjacent ones, two-directional electric fieldsalmost parallel with a surface of said first substrate is applied acrosssaid pixel electrode and said common electrode, said in-plane switchingmode active matrix type liquid crystal display device includes a firstsub pixel area to which an electric field having a first direction isapplied and in which molecular axes of liquid crystal in said liquidcrystal layer are rotated in a first rotational direction in a planeparallel with a surface of said first substrate, and a second sub pixelarea to which an electric field having a second direction is applied andin which said molecular axes are rotated in a second rotationaldirection which is different from said first rotational direction, in aplane parallel with a surface of said first substrate, an isolatedfloating electrode formed of a layer of which said gate electrode orsaid drain electrode is formed overlaps said common electrode or saidpixel electrode at bending portions of said zigzag-shaped common orpixel electrode with an insulating film being sandwiched therebetween,at least one of said common and pixel electrodes have a projectionprojecting from bending portions of said zigzag-shaped common and pixelelectrodes in a direction in which said bending portions project, alonga boundary between said first and second sub pixel areas.
 113. Anelectronic device including an in-plane switching mode active matrixtype liquid crystal display device comprised of: (a) a first substrate;(b) a second substrate located opposing said first substrate; and (c) aliquid crystal layer sandwiched between said first and secondsubstrates, wherein said first substrate includes: (a1) a thin filmtransistor having a gate electrode, a drain electrode and a sourceelectrode; (a2) a pixel electrode each associated to a pixel to bedriven; (a3) a common electrode to which a reference voltage is applied;(a4) data lines; (a5) a scanning line; and (a6) common electrode lines,said gate electrode is electrically connected to said scanning line,said drain electrode is electrically connected to said data lines, saidsource electrode is electrically connected to said pixel electrode, andsaid common electrode is electrically connected to said common electrodelines, molecular axes of liquid crystal in said liquid crystal layer arerotated in a plane parallel with said first substrate by an electricfield substantially parallel with a plane of said first substrate and tobe applied between said pixel electrode and said common electrode, tothereby display certain images, said common electrode is composed oftransparent material, and are formed on a layer located closer to saidliquid crystal layer than said data lines, said common electrodeentirely overlaps said data lines with an insulating layer beingsandwiched therebetween except an area where said data lines are locatedin the vicinity of said scanning line, said in-plane switching modeactive matrix type liquid crystal display device further includes alight-impermeable layer in an area where said common electrode entirelyoverlaps the data lines, said light-impermeable layer is formed on saidsecond substrate or on said first substrate such that saidlight-impermeable layer and said liquid crystal layer are located at thesame side with respect to said data lines and that saidlight-impermeable layer faces said data lines, said light-impermeablelayer is comprised of a black matrix layer or multi-layered colorlayers, said black matrix layer or said multi-layered color layers has awidth smaller than a width of said common electrode overlapping saiddata lines.
 114. An electronic device including an in-plane switchingmode active matrix type liquid crystal display device comprised of: (a)a first substrate; (b) a second substrate located opposing said firstsubstrate; and (c) a liquid crystal layer sandwiched between said firstand second substrates, wherein said first substrate includes: (a1) athin film transistor having a gate electrode, a drain electrode and asource electrode; (a2) a pixel electrode each associated to a pixel tobe driven; (a3) a common electrode to which a reference voltage isapplied; (a4) data lines; (a5) a scanning line; and (a6) commonelectrode lines, said gate electrode is electrically connected to saidscanning line, said drain electrode is electrically connected to saiddata lines, said source electrode is electrically connected to saidpixel electrode, and said common electrode is electrically connected tosaid common electrode lines, said pixel electrode is in a zigzag formand almost equally spaced away from adjacent ones, said common electrodeis in a zigzag form and almost equally spaced away from adjacent ones,two-directional electric fields almost parallel with a surface of saidfirst substrate are applied across said pixel electrode and said commonelectrode, said in-plane switching mode active matrix type liquidcrystal display device includes a first sub pixel area to which anelectric field having a first direction is applied and in whichmolecular axes of liquid crystal in said liquid crystal layer arerotated in a first rotational direction in a plane parallel with asurface of said first substrate, and a second sub pixel area to which anelectric field having a second direction is applied and in which saidmolecular axes are rotated in a second rotational direction which isdifferent from said first rotational direction, in a plane parallel witha surface of said first substrate, said common electrode is composed oftransparent material, and is formed on a layer located closer to saidliquid crystal layer than said data lines, said common electrodeentirely overlaps said data lines with an insulating layer beingsandwiched therebetween except an area where said data lines are locatedin the vicinity of said scanning line, said in-plane switching modeactive matrix type liquid crystal display device further includes alight-impermeable layer in an area where said common electrode entirelyoverlaps the data lines, said light-impermeable layer is formed on saidsecond substrate or on said first substrate such that saidlight-impermeable layer and said liquid crystal layer are located at thesame side with respect to said data lines and that saidlight-impermeable layer faces said data lines, said light-impermeablelayer is comprised of a black matrix layer or multi-layered colorlayers, said black matrix layer or said multi-layered color layers has awidth smaller than a width of said common electrode overlapping saiddata lines, said data lines extend in a zigzag along said pixelelectrode.
 115. An electronic device including an in-plane switchingmode active matrix type liquid crystal display device comprised of: (a)a first substrate; (b) a second substrate located opposing said firstsubstrate; and (c) a liquid crystal layer sandwiched between said firstand second substrates, wherein said first substrate includes: (a1) athin film transistor having a gate electrode, a drain electrode and asource electrode; (a2) a pixel electrode each associated to a pixel tobe driven; (a3) a common electrode to which a reference voltage isapplied; (a4) data lines; (a5) a scanning line; and (a6) commonelectrode lines, said gate electrode is electrically connected to saidscanning line, said drain electrode is electrically connected to saiddata lines, said source electrode is electrically connected to saidpixel electrode, and said common electrode is electrically connected tosaid common electrode lines, said pixel electrode is in a zigzag formand almost equally spaced away from adjacent ones; said common electrodeis in a zigzag form and almost equally spaced away from adjacent ones,two-directional electric fields almost parallel with a surface of saidfirst substrate are applied across said pixel electrode and said commonelectrode, said in-plane switching mode active matrix type liquidcrystal display device includes a first sub pixel area to which anelectric field having a first direction is applied and in whichmolecular axes of liquid crystal in said liquid crystal layer arerotated in a first rotational direction in a plane parallel with asurface of said first substrate, and a second sub pixel area to which anelectric field having a second direction is applied and in which saidmolecular axes are rotated in a second rotational direction which isdifferent from said first rotational direction, in a plane parallel witha surface of said first substrate, an opening of said first substrateextends in a direction perpendicular to a direction in which said datalines extend, said common electrode is composed of transparent material,and is formed on a layer located closer to said liquid crystal layerthan said data lines, said common electrode entirely overlaps said datalines with an insulating layer being sandwiched therebetween except anarea where said data lines are located in the vicinity of said scanningline, said common electrode is electrically connected to said commonelectrode lines through a contact hole in each of pixels, said in-planeswitching mode active matrix type liquid crystal display device furtherincludes a light-impermeable layer in an area where said commonelectrode entirely overlaps the data lines, said light-impermeable layeris formed on said second substrate or on said first substrate such thatsaid light-impermeable layer and said liquid crystal layer are locatedat the same side with respect to said data lines and that saidlight-impermeable layer faces said data lines, said light-impermeablelayer is comprised of a black matrix layer or multi-layered colorlayers, said black matrix layer or said multi-layered color layers has awidth smaller than a width of said common electrode overlapping saiddata lines, said data lines extends in a line, a gate line constitutessaid gate electrode extending in a zigzag.
 116. An electronic deviceincluding an in-plane switching mode active matrix type liquid crystaldisplay device comprised of: (a) a first substrate; (b) a secondsubstrate located opposing said first substrate; and (c) a liquidcrystal layer sandwiched between said first and second substrates,wherein said first substrate includes: (a1) a thin film transistorhaving a gate electrode, a drain electrode and a source electrode; (a2)a pixel electrode each associated to a pixel to be driven; (a3) a commonelectrode to which a reference voltage is applied; (a4) data lines; (a5)a scanning line; and (a6) common electrode lines, said gate electrode iselectrically connected to said scanning line, said drain electrode iselectrically connected to said data lines, said source electrode iselectrically connected to said pixel electrode, and said commonelectrode is electrically connected to said common electrode lines, saidpixel electrode is in a zigzag form and almost equally spaced away fromadjacent ones, said common electrode is in a zigzag form and almostequally spaced away from adjacent ones, two-directional electric fieldsalmost parallel with a surface of said first substrate is applied acrosssaid pixel electrode and said common electrode, said in-plane switchingmode active matrix type liquid crystal display device includes a firstsub pixel area to which an electric field having a first direction isapplied and in which molecular axes of liquid crystal in said liquidcrystal layer are rotated in a first rotational direction in a planeparallel with a surface of said first substrate, and a second sub pixelarea to which an electric field having a second direction is applied andin which said molecular axes are rotated in a second rotationaldirection which is different from said first rotational direction, in aplane parallel with a surface of said first substrate, said gateelectrode or an isolated floating electrode formed of a layer of whichsaid drain electrode is formed overlaps said common electrode or saidpixel electrode at bending portions of said zigzag-shaped common orpixel electrode with an insulating film being sandwiched therebetween,at least one of said common and pixel electrodes have a projectionprojecting from bending portions of said zigzag-shaped common and pixelelectrodes in a direction in which said bending portions project, alonga boundary between said first and second sub pixel areas.
 117. Theelectronic device as set forth in claim 114, wherein said in-planeswitching mode active matrix type liquid crystal display device furtherincludes a black matrix layer formed on said first substrate.
 118. Theelectronic device as set forth in claim 114, wherein said in-planeswitching mode active matrix type liquid crystal display device furtherincludes an interlayer insulating film formed between said data linesand said common electrode, said interlayer insulating film including atleast an organic film, said color or black matrix layer being coveredwith said organic film.
 119. A method of fabricating an in-planeswitching mode active matrix type liquid crystal display devicecomprising: (a) a first substrate; (b) a second substrate locatedopposing said first substrate; and (c) a liquid crystal layer sandwichedbetween said first and second substrates, wherein said first substrateincludes: (a1) a thin film transistor having a gate electrode, a drainelectrode and a source electrode; (a2) a pixel electrode each associatedto a pixel to be driven; (a3) a common electrode to which a referencevoltage is applied; (a4) data lines; (a5) a scanning line; (a6) commonelectrode lines; (a7) a data line terminal; (a8) a scanning lineterminal; and (a9) a common electrode line terminal, said gate electrodeis electrically connected to said scanning line, said drain electrode iselectrically connected to said data lines, said source electrode iselectrically connected to said pixel electrode, and said commonelectrode is electrically connected to said common electrode lines, andmolecular axes of liquid crystal in said liquid crystal layer arerotated in a plane parallel with said first substrate by an electricfield substantially parallel with a plane of said first substrate and tobe applied between said pixel electrode and said common electrode, tothereby display certain images, said method comprising the steps of: (a)forming said thin film transistor, said data lines, said scanning lineand said common electrode line, and thereafter, forming an interlayerinsulating film thereover; (b) etching said interlayer insulating filmto form contact holes reaching said data lines, said scanning line andsaid common electrode line; (c) deposit transparent metal all over aproduct resulted from said step (b) to cover inner surfaces of saidcontact holes with said transparent metal, thereby forming said dataline terminal, said scanning line terminal and said common electrodeline terminal; and (d) etching said transparent metal to form saidcommon electrode such that said common electrode overlaps said datalines.
 120. The method as set forth in claim 119, wherein saidtransparent metal is etched in said step (d) further for forming saidpixel electrode.
 121. The method as set forth in claim 119, wherein saidstep (b) includes the step of forming a second contact hole reachingsaid source electrode of said thin film transistor, and said step (c)includes the step of covering an inner surface of said second contacthole with said transparent metal.
 122. The method as set forth in claim119, wherein said step (b) includes the step of forming a third contacthole reaching said common electrode lines, said step (c) includes thestep of covering an inner surface of said third contact hole with saidtransparent metal, and said step (d) includes the step of etching saidtransparent metal to electrically connect said common electrode to saidthird contact hole.
 123. A method of fabricating an in-plane switchingmode active matrix type liquid crystal display device comprising: (a) afirst substrate; (b) a second substrate located opposing said firstsubstrate; and (c) a liquid crystal layer sandwiched between said firstand second substrates, wherein said first substrate includes: (a1) athin film transistor having a gate electrode, a drain electrode and asource electrode; (a2) a pixel electrode each associated to a pixel tobe driven; (a3) a common electrode to which a reference voltage isapplied; (a4) data lines; (a5) a scanning line; and (a6) commonelectrode lines, said gate electrode is electrically connected to saidscanning line, said drain electrode is electrically connected to saiddata lines, said source electrode is electrically connected to saidpixel electrode, and said common electrode is electrically connected tosaid common electrode lines, said pixel electrode is in a zigzag formand almost equally spaced away from adjacent ones, said common electrodeis in a zigzag form and almost equally spaced away from adjacent ones,two-directional electric fields almost parallel with a surface of saidfirst substrate are applied across said pixel electrode and said commonelectrode, said in-plane switching mode active matrix type liquidcrystal display device includes a first sub pixel area to which anelectric field having a first direction is applied and in whichmolecular axes of liquid crystal in said liquid crystal layer arerotated in a first rotational direction in a plane parallel with asurface of said first substrate, and a second sub pixel area to which anelectric field having a second direction is applied and in which saidmolecular axes are rotated in a second rotational direction which isdifferent from said first rotational direction, in a plane parallel witha surface of said first substrate, said method comprising the steps of:(a) forming said thin film transistor, said data lines, said scanningline and said common electrode line, and thereafter, forming aninterlayer insulating film thereover; (b) etching said interlayerinsulating film to form contact holes reaching said data lines, saidscanning line and said common electrode line; (c) deposit transparentmetal all over a product resulted from said step (b) to cover innersurfaces of said contact holes with said transparent metal, therebyforming said data line terminal, said scanning line terminal and saidcommon electrode line terminal; and (d) etching said transparent metalto form said common electrode such that said common electrode overlapssaid data lines.